x86, boot: Do not include boot.h in string.c

x86, boot: Do not include boot.h in string.c

string.c does not require whole of boot.h. Just inclusion of linux/types.h
and ctypes.h seems to be sufficient.

Keep list of stuff being included in string.c to bare minimal so that
string.c can be included in other places easily.

For example, Currently boot/compressed/string.c includes boot/string.c
but looks like it does not want boot/boot.h. Hence there is a define
in boot/compressed/misc.h "define BOOT_BOOT_H" which prevents inclusion
of boot.h in compressed/string.c. And compressed/string.c is forced to
include misc.h just for that reason.

So by removing inclusion of boot.h, we can also get rid of inclusion of
misch.h in compressed/misc.c.

This also enables including of boot/string.c in purgatory/ code relatively
easily.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Link: http://lkml.kernel.org/r/1398447972-27896-2-git-send-email-vgoyal@redhat.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>