i2c: Add module.h to modular files prev. implicitly getting it

These files use interfaces from linux/module.h, so they must
include that file to avoid build errors when the implicit
presence of module.h is removed.

[with i2c-pxa-pci.c fix from Randy Dunlap <rdunlap@xenotime.net>]

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>