agpgart.h: do not include <stdlib.h> from exported header

Commit 35d0f1d54ecd ("include/uapi/linux/agpgart.h: include stdlib.h in
userspace") included <stdlib.h> to fix the unknown size_t error, but
I do not think it is the right fix.

This header already uses __kernel_size_t a few lines below.

Replace the remaining size_t, and stop including <stdlib.h>.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

include/uapi/linux/agpgart.h: include stdlib.h in userspace

Fixes userspace compiler error:
error: unknown type name ‘size_t’

Signed-off-by: Mikko Rapeli <mikko.rapeli@iki.fi>

UAPI: (Scripted) Disintegrate include/linux

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>