reboot: move arch/x86 reboot= handling to generic kernel

Merge together the unicore32, arm, and x86 reboot= command line
parameter handling.

Signed-off-by: Robin Holt <holt@sgi.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Russ Anderson <rja@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 25dc4a0..75236f1 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2681,9 +2681,17 @@
 			Run specified binary instead of /init from the ramdisk,
 			used for early userspace startup. See initrd.
 
-	reboot=		[BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
-			Format: <reboot_mode>[,<reboot_mode2>[,...]]
-			See arch/*/kernel/reboot.c or arch/*/kernel/process.c
+	reboot=		[KNL]
+			Format (x86 or x86_64):
+				[w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
+				[[,]s[mp]#### \
+				[[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
+				[[,]f[orce]
+			Where reboot_mode is one of warm (soft) or cold (hard) or gpio,
+			      reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
+			      reboot_force is either force or not specified,
+			      reboot_cpu is s[mp]#### with #### being the processor
+					to be used for rebooting.
 
 	relax_domain_level=
 			[KNL, SMP] Set scheduler's default relax_domain_level.