soc/mediatek/common: Rename GPT_MHZ to TIMER_MHZ for readability

Update timer macro name for common.

The new ICs (e.g. mt8196, mt8189) will no longer use GPT. In order
to improve code readability, replace GPT_MHZ with TIMER_MHZ for
existing SoCs.

BUG=b:379008996
BRANCH=none
TEST=Build pass, Macro name is correct.

Change-Id: I02f18bfa5b5912f28e322d40cd46823a0095bbf4
Signed-off-by: Ke Zheng <ot_ke.zheng@mediatek.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/85681
Reviewed-by: Yidi Lin <yidilin@google.com>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/mediatek/common/include/soc/timer_v1.h

@@ -7,7 +7,7 @@
 #include <soc/timer_common.h>
 #include <types.h>
 
-#define GPT_MHZ	13
+#define TIMER_MHZ	13
 
 struct mtk_gpt_regs {
 	u32 reserved1[24];

src/soc/mediatek/common/include/soc/timer_v2.h

@@ -7,7 +7,7 @@
 #include <soc/timer_common.h>
 #include <types.h>
 
-#define GPT_MHZ	13
+#define TIMER_MHZ	13
 
 enum {
 	TIE_0_EN = 1 << 3,

src/soc/mediatek/common/timer.c

@@ -27,7 +27,7 @@ static uint64_t timer_raw_value(void)
 
 void timer_monotonic_get(struct mono_time *mt)
 {
-	mono_time_set_usecs(mt, timer_raw_value() / GPT_MHZ);
+	mono_time_set_usecs(mt, timer_raw_value() / TIMER_MHZ);
 }
 
 void init_timer(void)

src/soc/mediatek/mt8173/timer.c

@@ -18,5 +18,5 @@ void timer_prepare(void)
 	 */
 	write32(&mt8173_mcucfg->xgpt_idx, 0);
 	/* Set clock mode to 13Mhz and enable XGPT */
-	write32(&mt8173_mcucfg->xgpt_ctl, (0x1 | ((26 / GPT_MHZ) << 8)));
+	write32(&mt8173_mcucfg->xgpt_ctl, (0x1 | ((26 / TIMER_MHZ) << 8)));
 }

src/soc/mediatek/mt8196/timer.c

@@ -9,5 +9,5 @@ void init_timer(void)
 {
 	timer_prepare();
 
-	raw_write_cntfrq_el0(GPT_MHZ * MHz);
+	raw_write_cntfrq_el0(TIMER_MHZ * MHz);
 }