tty: serial: bcm63xx_uart: remove unused inclusion

bcm63xx_irqs.h is included but we are not using anything from it, drop
that include.
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6205/

drivers/tty/serial/bcm63xx_uart.c

@@ -30,7 +30,6 @@
 #include <linux/serial.h>
 #include <linux/serial_core.h>
 
-#include <bcm63xx_irq.h>
 #include <bcm63xx_regs.h>
 #include <bcm63xx_io.h>