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>

src/soc/sifive/fu540/cbmem.c

@@ -6,8 +6,7 @@
 #include <soc/sdram.h>
 #include <symbols.h>
 
-void *cbmem_top_chipset(void)
+uintptr_t cbmem_top_chipset(void)
 {
-	return (void *)MIN((uintptr_t)_dram + sdram_size_mb() * MiB,
-			   FU540_MAXDRAM);
+	return MIN((uintptr_t)_dram + sdram_size_mb() * MiB, FU540_MAXDRAM);
 }