haswell/broadwell: Replace remaining MCHBAR accessors

Tested with BUILD_TIMELESS=1, Asrock B85M Pro4 and Purism Librem 13 v1
remain identical.

Change-Id: I74b633fb0b012304b5b4bd943272ed82dcb6f7d5
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52468
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/intel/broadwell/gma.c b/src/soc/intel/broadwell/gma.c
index 59379b5..1e25502 100644
--- a/src/soc/intel/broadwell/gma.c
+++ b/src/soc/intel/broadwell/gma.c
@@ -529,7 +529,7 @@
 	}
 
 	/* Set RP1 graphics frequency */
-	rp1_gfx_freq = (MCHBAR32(0x5998) >> 8) & 0xff;
+	rp1_gfx_freq = (mchbar_read32(0x5998) >> 8) & 0xff;
 	gtt_write(0xa008, rp1_gfx_freq << 24);
 
 	/* Post VBIOS panel setup */