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/arch/arm64/romstage.c

@@ -12,7 +12,7 @@ __weak void platform_romstage_postram(void) { /* no-op */ }
 
 void main(void)
 {
-	timestamp_add_now(TS_START_ROMSTAGE);
+	timestamp_add_now(TS_ROMSTAGE_START);
 
 	console_init();
 	exception_init();

src/arch/x86/postcar.c

@@ -30,7 +30,7 @@ void main(void)
 	if (!cbmem_online())
 		cbmem_initialize();
 
-	timestamp_add_now(TS_START_POSTCAR);
+	timestamp_add_now(TS_POSTCAR_START);
 
 	display_mtrrs();
 

src/arch/x86/postcar_loader.c

@@ -192,7 +192,7 @@ void run_postcar_phase(struct postcar_frame *pcf)
 		load_postcar_cbfs(&prog, pcf);
 
 	/* As postcar exist, it's end of romstage here */
-	timestamp_add_now(TS_END_ROMSTAGE);
+	timestamp_add_now(TS_ROMSTAGE_END);
 
 	console_time_report();