mb/google/bluey: Lower CPU frequency to 710.4MHz for low-power boot

In scenarios where the system is booting with a critical or low battery,
lowering the initial CPU frequency helps reduce the instantaneous power
draw, ensuring the battery can sustain the boot process while fast
charging is being enabled.

Changes:
- clock.h: Replace 806MHz (0x2A) with 710.4MHz (0x25) based on 19.2MHz
  XO.
- mainboard.c: Update handle_low_power_charging_boot() to use the
  new L-VAL and update the debug log accordingly.

BUG=b:436391478

Change-Id: Ida30824e344a4613c797083711c3f6ee31f9694d
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/91838
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-by: Jayvik Desai <jayvik@google.com>

src/mainboard/google/bluey/mainboard.c

@@ -188,8 +188,8 @@ static void trigger_critical_battery_shutdown(void)
  */
 static void handle_low_power_charging_boot(void)
 {
-	if (!pll_init_and_set(apss_ncc0, L_VAL_806MHz))
-		printk(BIOS_DEBUG, "CPU Frequency set to 806MHz\n");
+	if (!pll_init_and_set(apss_ncc0, L_VAL_710P4MHz))
+		printk(BIOS_DEBUG, "CPU Frequency set to 710MHz\n");
 
 	enable_fast_battery_charging();
 

src/soc/qualcomm/x1p42100/include/soc/clock.h

@@ -21,7 +21,7 @@
 /* CPU PLL*/
 #define L_VAL_2995P2MHz		0x9C
 #define L_VAL_1363P2MHz		0x47
-#define L_VAL_806MHz		0x2A
+#define L_VAL_710P4MHz		0x25
 
 /* DISP PLL */
 #define L_VAL_1725MHz		0x59