[POWERPC] therm_pm72: Suppress some compile warnings

We don't really care if any of these calls to device_create_file fails,
so just issue warnings in that case.

drivers/macintosh/therm_pm72.c: In function 'init_cpu_state':
drivers/macintosh/therm_pm72.c:1185: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c:1186: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c:1187: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c:1188: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c:1189: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c:1191: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c:1192: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c:1193: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c:1194: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c:1195: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c: In function 'init_backside_state':
drivers/macintosh/therm_pm72.c:1383: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c:1384: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c: In function 'init_drives_state':
drivers/macintosh/therm_pm72.c:1503: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c:1504: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c: In function 'init_dimms_state':
drivers/macintosh/therm_pm72.c:1625: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c: In function 'init_slots_state':
drivers/macintosh/therm_pm72.c:1743: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result
drivers/macintosh/therm_pm72.c:1744: warning: ignoring return value of 'device_create_file', declared with attribute warn_unused_result

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>