ramips: mt7621: (APP-3302, PR #286) Move PWM LED from kmod to kernel builtin

The status LED is now driven by the PWM driver. When the driver is built as
a kmod module, it is loaded after the preinit state is set. This means
the diag.sh script cannot set the color and flashing pattern. Making the
driver built in means the LED can be controlled at preinit stage.

Approved-by: James Haggerty
Approved-by: Sophronia Koilpillai

target/linux/ramips/image/mt7621.mk

@@ -1684,7 +1684,7 @@ define Device/morse_artini
   # If $1=squashfs remove, likewise with $2=sysupgrade.bin, for simpler names.
   # So a 'normal' Artini image will look like openwrt-morse-2.7.0-artini.bin
   DEVICE_IMG_NAME = $(VERSION_DIST_SANITIZED)-$$(IMG_PREFIX_VERCODE)$$(call sanitize,$$(DEVICE_MODEL))$$(if $$(filter-out squashfs,$$(1)),-$$(1),'')$$(if $$(filter-out sysupgrade.bin, $$(2)),-$$(2),.bin)
-  DEVICE_PACKAGES := kmod-mmc-mt7620 kmod-mt7603 kmod-pwm-gpio kmod-leds-pwm-multicolor \
+  DEVICE_PACKAGES := kmod-mmc-mt7620 kmod-mt7603 \
 	kmod-morse netifd-morse
 endef
 TARGET_DEVICES += morse_artini

target/linux/ramips/mt7621/config-5.15

@@ -104,6 +104,7 @@ CONFIG_IRQ_DOMAIN_HIERARCHY=y
 CONFIG_IRQ_FORCED_THREADING=y
 CONFIG_IRQ_MIPS_CPU=y
 CONFIG_IRQ_WORK=y
+CONFIG_LEDS_PWM_MULTICOLOR=y
 CONFIG_LED_TRIGGER_PHY=y
 CONFIG_LIBFDT=y
 CONFIG_LOCK_DEBUGGING_SUPPORT=y
@@ -221,6 +222,10 @@ CONFIG_POWER_RESET=y
 CONFIG_POWER_RESET_GPIO=y
 CONFIG_POWER_SUPPLY=y
 CONFIG_PTP_1588_CLOCK_OPTIONAL=y
+CONFIG_PWM=y
+CONFIG_PWM_GPIO=y
+# CONFIG_PWM_MEDIATEK_RAMIPS is not set
+CONFIG_PWM_SYSFS=y
 CONFIG_QUEUED_RWLOCKS=y
 CONFIG_QUEUED_SPINLOCKS=y
 CONFIG_RALINK=y