mxs: Convert sys_proto.h prefixes to 'mxs'

The sys_proto.h functions (except the boot modes) are compatible with
i.MX233 and i.MX28 so we use 'mxs' prefix for its methods.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
diff --git a/drivers/spi/mxs_spi.c b/drivers/spi/mxs_spi.c
index bd834fb..a037c13 100644
--- a/drivers/spi/mxs_spi.c
+++ b/drivers/spi/mxs_spi.c
@@ -139,7 +139,7 @@
 	struct mxs_ssp_regs *ssp_regs = mxs_slave->regs;
 	uint32_t reg = 0;
 
-	mx28_reset_block(&ssp_regs->hw_ssp_ctrl0_reg);
+	mxs_reset_block(&ssp_regs->hw_ssp_ctrl0_reg);
 
 	writel(SSP_CTRL0_BUS_WIDTH_ONE_BIT, &ssp_regs->hw_ssp_ctrl0);
 
@@ -193,7 +193,7 @@
 
 		writel(SSP_CTRL0_RUN, &ssp_regs->hw_ssp_ctrl0_set);
 
-		if (mx28_wait_mask_set(&ssp_regs->hw_ssp_ctrl0_reg,
+		if (mxs_wait_mask_set(&ssp_regs->hw_ssp_ctrl0_reg,
 			SSP_CTRL0_RUN, MXS_SPI_MAX_TIMEOUT)) {
 			printf("MXS SPI: Timeout waiting for start\n");
 			return -ETIMEDOUT;
@@ -205,7 +205,7 @@
 		writel(SSP_CTRL0_DATA_XFER, &ssp_regs->hw_ssp_ctrl0_set);
 
 		if (!write) {
-			if (mx28_wait_mask_clr(&ssp_regs->hw_ssp_status_reg,
+			if (mxs_wait_mask_clr(&ssp_regs->hw_ssp_status_reg,
 				SSP_STATUS_FIFO_EMPTY, MXS_SPI_MAX_TIMEOUT)) {
 				printf("MXS SPI: Timeout waiting for data\n");
 				return -ETIMEDOUT;
@@ -215,7 +215,7 @@
 			data++;
 		}
 
-		if (mx28_wait_mask_clr(&ssp_regs->hw_ssp_ctrl0_reg,
+		if (mxs_wait_mask_clr(&ssp_regs->hw_ssp_ctrl0_reg,
 			SSP_CTRL0_RUN, MXS_SPI_MAX_TIMEOUT)) {
 			printf("MXS SPI: Timeout waiting for finish\n");
 			return -ETIMEDOUT;