reboot: arm: change reboot_mode to use enum reboot_mode

reboot: arm: change reboot_mode to use enum reboot_mode

Preparing to move the parsing of reboot= to generic kernel code forces
the change in reboot_mode handling to use the enum.

[[email protected]: fix arch/arm/mach-socfpga/socfpga.c]
Signed-off-by: Robin Holt <[email protected]>
Cc: Russell King <[email protected]>
Cc: Russ Anderson <[email protected]>
Cc: Robin Holt <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Guan Xuetao <[email protected]>
Acked-by: Russell King <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>