ARM: at91: fix pm declarations

In a recent rearrangement of the at91 pm initialization code, a broken
set of declarations was added for the !CONFIG_PM-case, leading to
this link error:

arch/arm/mach-at91/board-dt-sama5.o: In function `at91_rm9200_pm_init':
arch/arm/mach-at91/generic.h:40: multiple definition of `at91_rm9200_pm_init'
arch/arm/mach-at91/setup.o:arch/arm/mach-at91/generic.h:40: first defined here
arch/arm/mach-at91/board-dt-sama5.o: In function `at91_sam9260_pm_init':
arch/arm/mach-at91/generic.h:41: multiple definition of `at91_sam9260_pm_init'
arch/arm/mach-at91/setup.o:arch/arm/mach-at91/generic.h:41: first defined here
arch/arm/mach-at91/board-dt-sama5.o: In function `at91_sam9g45_pm_init':
arch/arm/mach-at91/generic.h:42: multiple definition of `at91_sam9g45_pm_init'
arch/arm/mach-at91/setup.o:arch/arm/mach-at91/generic.h:42: first defined here

This adds the missing 'static inline' to the declarations to avoid
creating a copy of the functions in each file that includes the
header.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 4db0ba22 ("ARM: at91: pm: prepare for multiplatform")
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>