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

Commit 35d0f1d5 ("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

@@ -52,7 +52,6 @@
 
 #ifndef __KERNEL__
 #include <linux/types.h>
-#include <stdlib.h>
 
 struct agp_version {
 	__u16 major;
@@ -64,10 +63,10 @@ typedef struct _agp_info {
 	__u32 bridge_id;	/* bridge vendor/device         */
 	__u32 agp_mode;		/* mode info of bridge          */
 	unsigned long aper_base;/* base of aperture             */
-	size_t aper_size;	/* size of aperture             */
-	size_t pg_total;	/* max pages (swap + system)    */
-	size_t pg_system;	/* max pages (system)           */
-	size_t pg_used;		/* current pages used           */
+	__kernel_size_t aper_size;	/* size of aperture             */
+	__kernel_size_t pg_total;	/* max pages (swap + system)    */
+	__kernel_size_t pg_system;	/* max pages (system)           */
+	__kernel_size_t pg_used;	/* current pages used           */
 } agp_info;
 
 typedef struct _agp_setup {