vc_sm: Let it support to build in the non-src folder

If we build the kernel with "-O=$non-src-folder", this driver will
introdcue a building error because of the header's location.

Signed-off-by: Hui Wang <[email protected]>

Author: jason77-wang

drivers/char/broadcom/vc_sm/Makefile

@@ -1,5 +1,5 @@
 ccflags-$(CONFIG_BCM_VC_SM) += -Werror -Wall -Wstrict-prototypes -Wno-trigraphs -O2
-ccflags-$(CONFIG_BCM_VC_SM) += -I"drivers/staging/vc04_services" -I"drivers/staging/vc04_services/interface/vchi" -I"drivers/staging/vc04_services/interface/vchiq_arm" -I"fs"
+ccflags-$(CONFIG_BCM_VC_SM) += -I$(srctree)/"drivers/staging/vc04_services" -I$(srctree)/"drivers/staging/vc04_services/interface/vchi" -I$(srctree)/"drivers/staging/vc04_services/interface/vchiq_arm" -I$(srctree)/"fs"
 ccflags-$(CONFIG_BCM_VC_SM) += -DOS_ASSERT_FAILURE -D__STDC_VERSION=199901L -D__STDC_VERSION__=199901L -D__VCCOREVER__=0 -D__KERNEL__ -D__linux__
 
 obj-$(CONFIG_BCM_VC_SM) := vc-sm.o