arm64: Enable BCM7038_L1_IRQ for ARCH_BRCMSTB

ARCH_BRCMSTB makes use of the irq-bcm7038-l1.c irqchip driver, enable
it.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

arch/arm64/Kconfig.platforms

@@ -65,6 +65,7 @@ config ARCH_BITMAIN
 
 config ARCH_BRCMSTB
 	bool "Broadcom Set-Top-Box SoCs"
+	select BCM7038_L1_IRQ
 	select BRCMSTB_L2_IRQ
 	select GENERIC_IRQ_CHIP
 	help