ARM: at91/power/reset: fix Kconfig "depends on" directive
ARM: at91/power/reset: fix Kconfig "depends on" directive

MACH_AT91 doesn't exist so we can't "depend" on it. Fix the typo
by using the proper ARCH_AT91 config option.

Signed-off-by: Nicolas Ferre <45b517be0e5ec6dc3a39715767c1d18e090d39b4@atmel.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs