[ARM] pass reboot command line to arch_reset()

OMAP wishes to pass state to the boot loader upon reboot in order to
instruct it whether to wait for USB-based reflashing or not.  There is
already a facility to do this via the reboot() syscall, except we ignore
the string passed to machine_restart().

This patch fixes things to pass this string to arch_reset().  This means
that we keep the reboot mode limited to telling the kernel _how_ to
perform the reboot which should be independent of what we request the
boot loader to do.

Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-davinci/include/mach/system.h

@@ -21,7 +21,7 @@ static void arch_idle(void)
 	cpu_do_idle();
 }
 
-static void arch_reset(char mode)
+static void arch_reset(char mode, const char *cmd)
 {
 	davinci_watchdog_reset();
 }