avoid out-of-bounds warnings with recent compilers

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/hwsetup.c b/hwsetup.c
index e8a452e..617af06 100644
--- a/hwsetup.c
+++ b/hwsetup.c
@@ -97,8 +97,8 @@
 void setup_hw(void)
 {
 	const int bdf = 0;
-	const uint8_t *bios_start = &stext + 0xfff00000;
-	const uint8_t *init_start = &sinit + 0xfff00000;
+	const uint8_t *bios_start = (void *)((uintptr_t)&stext + 0xfff00000);
+	const uint8_t *init_start = (void *)((uintptr_t)&sinit + 0xfff00000);
 	volatile uint8_t *rom_check = &stext;
 	int rom_check_value;
 	int pambase;