x86, 8042: Enable A20 using KBC to fix S3 resume on some MSI laptops

x86, 8042: Enable A20 using KBC to fix S3 resume on some MSI laptops

Some MSI laptop BIOSes are broken - INT 15h code uses port 92h to enable A20
line but resume code assumes that KBC was used.
The laptop will not resume from S3 otherwise but powers off after a while
and then powers on again stuck with a blank screen.

Fix it by enabling A20 using KBC in i8042_platform_init for x86.

Fixes https://bugzilla.kernel.org/show_bug.cgi?id=12878

Signed-off-by: Ondrej Zary <[email protected]>
Cc: Dmitry Torokhov <[email protected]>
Cc: Alan Cox <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: H. Peter Anvin <[email protected]>