spi: Avoid signed shifts

Shifting signed types to the left is dodgy, especially by 31 bits, since
it depends on the result type whether the result is undefined or not.

Do not take any chances here, and mark those shift bases as unsigned where
we can or will hit bit 31, to avoid undefined behaviour.
Signed-off-by: Andre Przywara <osp@andrep.de>

fel-spiflash.c

@@ -94,7 +94,7 @@ void fel_writel(feldev_handle *dev, uint32_t addr, uint32_t val);
 #define SUN4I_CTL_RF_RST            (1 << 9)
 #define SUN4I_CTL_XCH               (1 << 10)
 
-#define SUN6I_TCR_XCH               (1 << 31)
+#define SUN6I_TCR_XCH               (1U << 31)
 
 #define SUN4I_SPI0_CCTL             (spi_base(dev) + 0x1C)
 #define SUN4I_SPI0_CTL              (spi_base(dev) + 0x08)
@@ -271,10 +271,10 @@ static bool spi0_init(feldev_handle *dev)
 	if (spi_is_sun6i(dev)) {
 		/* Enable SPI in the master mode and do a soft reset */
 		reg_val = readl(SUN6I_SPI0_GCR);
-		reg_val |= (1 << 31) | 3;
+		reg_val |= (1U << 31) | 3;
 		writel(reg_val, SUN6I_SPI0_GCR);
 		/* Wait for completion */
-		while (readl(SUN6I_SPI0_GCR) & (1 << 31)) {}
+		while (readl(SUN6I_SPI0_GCR) & (1U << 31)) {}
 	} else {
 		reg_val = readl(SUN4I_SPI0_CTL);
 		reg_val |= SUN4I_CTL_MASTER;
@@ -555,7 +555,7 @@ void aw_fel_spiflash_info(feldev_handle *dev)
 	}
 
 	printf("Manufacturer: %s (%02Xh), model: %02Xh, size: %d bytes.\n",
-	       manufacturer, buf[3], buf[4], (1 << buf[5]));
+	       manufacturer, buf[3], buf[4], (1U << buf[5]));
 }
 
 /*