serial: fix UART_IIR_ID
serial: fix UART_IIR_ID

UART IRQ Identification bitfield is 3
bits long (bits 3:1) but current mask only
masks 2 bits. Fix it.

Signed-off-by: Felipe Balbi <94dddeeef08b001e003cce128ddc162a4e2c6cd2@ti.com>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@linuxfoundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs