MAINTAINERS: Add Watchdog and RTC files to STI's maintainer entry

Signed-off-by: Lee Jones <lee.jones@linaro.org>

MAINTAINERS

@@ -1473,10 +1473,12 @@ F:	drivers/phy/phy-stih407-usb.c
 F:	drivers/phy/phy-stih41x-usb.c
 F:	drivers/pinctrl/pinctrl-st.c
 F:	drivers/reset/sti/
+F:	drivers/rtc/rtc-st-lpc.c
 F:	drivers/tty/serial/st-asc.c
 F:	drivers/usb/dwc3/dwc3-st.c
 F:	drivers/usb/host/ehci-st.c
 F:	drivers/usb/host/ohci-st.c
+F:	drivers/watchdog/st_lpc_wdt.c
 F:	drivers/ata/ahci_st.c
 
 ARM/TECHNOLOGIC SYSTEMS TS7250 MACHINE SUPPORT