power: reset: Allow selecting POWER_RESET_BRCMSTB on ARM64

Since commit 37eb56dc ("arm64: Add Broadcom Set Top Box Kconfig
entry point") we have ARCH_BRCMSTB also visible on ARM64 platform, yet
this reboot driver was not selectable, so fix that.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

drivers/power/reset/Kconfig

@@ -58,7 +58,7 @@ config POWER_RESET_BRCMKONA
 
 config POWER_RESET_BRCMSTB
 	bool "Broadcom STB reset driver"
-	depends on ARM || MIPS || COMPILE_TEST
+	depends on ARM || ARM64 || MIPS || COMPILE_TEST
 	depends on MFD_SYSCON
 	default ARCH_BRCMSTB
 	help