MAINTAINERS: Add more sources to Arch Snapdragon

Add scattered driver files around the source tree
that belongs to Snapdragon arch. Not sure why they
were not included in the first place.
Signed-off-by: NRamon Fried <ramon.fried@gmail.com>

MAINTAINERS

@@ -207,7 +207,11 @@ ARM SNAPDRAGON
 M:	Ramon Fried <ramon.fried@gmail.com>
 S:	Maintained
 F:	arch/arm/mach-snapdragon/
+F:	drivers/gpio/msm_gpio.c
+F:	drivers/mmc/msm_sdhci.c
+F:	drivers/serial/serial_msm.c
 F:	drivers/smem/msm_smem.c
+F:	drivers/usb/host/ehci-msm.c
 
 ARM STI
 M:	Patrice Chotard <patrice.chotard@st.com>