include/cpu/amd/mtrr: rename functions to get top of memory regions

Rename amd_topmem and amd_topmem2 to get_top_of_mem_below_4gb and
get_top_of_mem_above_4g to make it clearer what those functions return.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: Ic6e98d94c731af74aea0ce276a9a7e4867e3986f
Reviewed-on: https://review.coreboot.org/c/coreboot/+/74589
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martin.roth@amd.corp-partner.google.com>
diff --git a/src/northbridge/amd/pi/00730F01/northbridge.c b/src/northbridge/amd/pi/00730F01/northbridge.c
index 5f3b4d9..d963171 100644
--- a/src/northbridge/amd/pi/00730F01/northbridge.c
+++ b/src/northbridge/amd/pi/00730F01/northbridge.c
@@ -781,7 +781,7 @@
 	pci_domain_read_resources(dev);
 
 	/* TOP_MEM MSR is our boundary between DRAM and MMIO under 4G */
-	mmio_basek = amd_topmem() >> 10;
+	mmio_basek = get_top_of_mem_below_4gb() >> 10;
 
 #if CONFIG_HW_MEM_HOLE_SIZEK != 0
 	/* if the hw mem hole is already set in raminit stage, here we will compare
@@ -837,7 +837,7 @@
 				sizek = 0;
 			}
 			else {
-				uint64_t topmem2 = amd_topmem2();
+				uint64_t topmem2 = get_top_of_mem_above_4g();
 				basek = 4 * 1024 * 1024;
 				sizek = topmem2 / 1024 - basek;
 			}