MAINTAINERS: Include Samsung PWM in Samsung SoC entry

The Samsung PWM and PWM-based timer/clocksource drivers lacked dedicated
maintainers entry.  They are used on all Samsung SoC designs (although
timer/clocksource driver only on older platforms), so include them in
Samsung SoC entry maintained by Krzysztof Kozlowski.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20210506202729.157260-5-krzysztof.kozlowski@canonical.com

MAINTAINERS

@@ -2436,9 +2436,12 @@ F:	drivers/*/*/*s3c24*
 F:	drivers/*/*s3c24*
 F:	drivers/*/*s3c64xx*
 F:	drivers/*/*s5pv210*
+F:	drivers/clocksource/samsung_pwm_timer.c
 F:	drivers/memory/samsung/
+F:	drivers/pwm/pwm-samsung.c
 F:	drivers/soc/samsung/
 F:	drivers/tty/serial/samsung*
+F:	include/clocksource/samsung_pwm.h
 F:	include/linux/platform_data/*s3c*
 F:	include/linux/serial_s3c.h
 F:	include/linux/soc/samsung/