Revert "Disable the 8042 MUX on our x86 devices."

This reverts commit 4deda9c24f1deb015946c709d1d3d11f1c0e2325.

BUG=chrome-os-partner:2811, chromium-os:13101
TEST=boot and verify /proc/cmdline
TBR=puneetster

Change-Id: I52990abc01fe5fc2d160d8efbb0a14bff1943ae4
(cherry picked from commit 1649ba8c1be54ca34355198ab3808a0d7480c484)
diff --git a/build_kernel_image.sh b/build_kernel_image.sh
index 6f87ebe..5ee3e30 100755
--- a/build_kernel_image.sh
+++ b/build_kernel_image.sh
@@ -168,7 +168,6 @@
 tpm_tis.force=1
 tpm_tis.interrupts=0
 nmi_watchdog=panic,lapic
-i8042.nomux=1
 EOF
   WORK="${WORK} ${FLAGS_working_dir}/config.txt"