ARM: bL_switcher: add a simple /dev user interface for debugging purposes

Only the basic call to aid debugging.

*** NOT FOR PRODUCTION ***

Usage:

	echo <cpuid>,<clusterid> > /dev/b.L_switcher

where <cpuid> is the logical CPU number, and <clusterid> is 0 for the
first cluster and 1 for the second cluster.

Signed-off-by: nicolas Pitre <nico@linaro.org>
diff --git a/arch/arm/common/Makefile b/arch/arm/common/Makefile
index 2586240..5c8584c 100644
--- a/arch/arm/common/Makefile
+++ b/arch/arm/common/Makefile
@@ -18,3 +18,4 @@
 AFLAGS_vlock.o			:= -march=armv7-a
 obj-$(CONFIG_TI_PRIV_EDMA)	+= edma.o
 obj-$(CONFIG_BL_SWITCHER)	+= bL_switcher.o
+obj-$(CONFIG_BL_SWITCHER_DUMMY_IF) += bL_switcher_dummy_if.o