cbmem_top_chipset: Change the return value to uintptr_t

Get rid of a lot of casts.

Change-Id: I93645ef5dd270905ce421e68e342aff4c331eae6
Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69078
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jakub Czapiga <jacz@semihalf.com>
diff --git a/src/northbridge/intel/haswell/memmap.c b/src/northbridge/intel/haswell/memmap.c
index c19cfec..6b75caa 100644
--- a/src/northbridge/intel/haswell/memmap.c
+++ b/src/northbridge/intel/haswell/memmap.c
@@ -54,9 +54,9 @@
 	return tolum;
 }
 
-void *cbmem_top_chipset(void)
+uintptr_t cbmem_top_chipset(void)
 {
-	return (void *)top_of_low_usable_memory();
+	return top_of_low_usable_memory();
 }
 
 void smm_region(uintptr_t *start, size_t *size)