timestamps: Rename timestamps to make names more consistent

This patch aims to make timestamps more consistent in naming,
to follow one pattern. Until now there were many naming patterns:
- TS_START_*/TS_END_*
- TS_BEFORE_*/TS_AFTER_*
- TS_*_START/TS_*_END
This change also aims to indicate, that these timestamps can be used
to create time-ranges, e.g. from TS_BOOTBLOCK_START to TS_BOOTBLOCK_END.

Signed-off-by: Jakub Czapiga <jacz@semihalf.com>
Change-Id: I533e32392224d9b67c37e6a67987b09bf1cf51c6
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62019
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Raul Rangel <rrangel@chromium.org>

src/northbridge/intel/gm45/raminit.c

@@ -1695,7 +1695,7 @@ void raminit(sysinfo_t *const sysinfo, const int s3resume)
 
 	int ch;
 
-	timestamp_add_now(TS_BEFORE_INITRAM);
+	timestamp_add_now(TS_INITRAM_START);
 
 	/* Wait for some bit, maybe TXT clear. */
 	if (sysinfo->txt_enabled) {
@@ -1803,5 +1803,5 @@ void raminit(sysinfo_t *const sysinfo, const int s3resume)
 	raminit_thermal(sysinfo);
 	init_igd(sysinfo);
 
-	timestamp_add_now(TS_AFTER_INITRAM);
+	timestamp_add_now(TS_INITRAM_END);
 }