Revert "x86/early_printk: Replace obsolete simple_strtoul() usage with kstrtoint()"

This reverts commit fbd24153c48b8425b09c161a020483cd77da870e.

This commit is subtly buggy: kstrto*int() can return an error but
it's not checked in every path. simple_strtoul() on the other hand
could not fail, so this patch subtly intruduces new failure modes.

Signed-off-by: Shuah Khan <shuahkhan@gmail.com>
Link: http://lkml.kernel.org/r/1338424803.3569.5.camel@lorien2
Signed-off-by: Ingo Molnar <mingo@kernel.org>