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>

src/include/cpu/amd/mtrr.h

@@ -65,12 +65,12 @@ static __always_inline void wrmsr_amd(unsigned int index, msr_t msr)
 		);
 }
 
-static inline uint64_t amd_topmem(void)
+static inline uint64_t get_top_of_mem_below_4gb(void)
 {
 	return rdmsr(TOP_MEM).lo;
 }
 
-static inline uint64_t amd_topmem2(void)
+static inline uint64_t get_top_of_mem_above_4g(void)
 {
 	msr_t msr = rdmsr(TOP_MEM2);
 	return (uint64_t)msr.hi << 32 | msr.lo;