ARM: pxa: mark ezx structures as __maybe_unused

The ezx platform contains multiple machine descriptors, but not all
of them use all of the data structures, and it's possible to disable
all of the machines, which produces some harmless warnings:

mach-pxa/ezx.c:53:26: warning: 'ezx_pwm_lookup' defined but not used [-Wunused-variable]
mach-pxa/ezx.c:86:31: warning: 'ezx_fb_info_1' defined but not used [-Wunused-variable]
mach-pxa/ezx.c:107:31: warning: 'ezx_fb_info_2' defined but not used [-Wunused-variable]
mach-pxa/ezx.c:113:32: warning: 'ezx_devices' defined but not used [-Wunused-variable]
mach-pxa/ezx.c:117:22: warning: 'ezx_pin_config' defined but not used [-Wunused-variable]

This marks all those structures as __maybe_unused to avoid the warnings.
Obviously a configuration that contains the ezx platform but no specific
model is a bit silly, but it should not cause compile-time warnings.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>