bus: brcmstb_gisb: Make the driver buildable on MIPS

BCM7xxx ARM and MIPS platforms share a similar hardware block for
reporting GISB errors, so they both benefit from the use of this driver.
Conditionally compile the ARM-specific bus error handler so that the
GISB error IRQ handler works on other architectures.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 603eb1b..b99729e 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -6,7 +6,7 @@
 
 config BRCMSTB_GISB_ARB
 	bool "Broadcom STB GISB bus arbiter"
-	depends on ARM
+	depends on ARM || MIPS
 	help
 	  Driver for the Broadcom Set Top Box System-on-a-chip internal bus
 	  arbiter. This driver provides timeout and target abort error handling