[ARM] 5330/1: mach-pxa: Fixup reset for systems using reboot=cold or other strings

This patch makes do_hw_reset the default reboot behavior when nothing
else matches. This restores reboot functionality on gumstix basix
devices where reboot=cold is the default boot argument.

Signed-off-by: Jaya Kumar <jayakumar.lkml@gmail.com>
Acked-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>