mach-u300: set apropriate FIFO trigger levels

The U300 just defined the fill level limits for the FIFOs to
1 item out of habit. It can easily handle four.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/arch/arm/mach-u300/spi.c b/arch/arm/mach-u300/spi.c
index 5767208..7b597e2 100644
--- a/arch/arm/mach-u300/spi.c
+++ b/arch/arm/mach-u300/spi.c
@@ -40,8 +40,8 @@
 	.hierarchy = SSP_MASTER,
 	/* 0 = drive TX even as slave, 1 = do not drive TX as slave */
 	.slave_tx_disable = 0,
-	.rx_lev_trig = SSP_RX_1_OR_MORE_ELEM,
-	.tx_lev_trig = SSP_TX_1_OR_MORE_EMPTY_LOC,
+	.rx_lev_trig = SSP_RX_4_OR_MORE_ELEM,
+	.tx_lev_trig = SSP_TX_4_OR_MORE_EMPTY_LOC,
 	.ctrl_len = SSP_BITS_12,
 	.wait_state = SSP_MWIRE_WAIT_ZERO,
 	.duplex = SSP_MICROWIRE_CHANNEL_FULL_DUPLEX,