lcd: Fix build error with CONFIG_LCD_BMP_RLE8

Add a block to avoid a build error with the variable declaration.
Enable the option on sandbox to prevent an error being introduced in
future.

Signed-off-by: Simon Glass <sjg@chromium.org>

common/lcd.c

@@ -1023,7 +1023,7 @@ int lcd_display_bitmap(ulong bmp_image, int x, int y)
 
 	switch (bmp_bpix) {
 	case 1: /* pass through */
-	case 8:
+	case 8: {
 #ifdef CONFIG_LCD_BMP_RLE8
 		u32 compression = get_unaligned_le32(&bmp->header.compression);
 		if (compression == BMP_BI_RLE8) {
@@ -1056,7 +1056,7 @@ int lcd_display_bitmap(ulong bmp_image, int x, int y)
 			fb -= byte_width + lcd_line_length;
 		}
 		break;
-
+	}
 #if defined(CONFIG_BMP_16BPP)
 	case 16:
 		for (i = 0; i < height; ++i) {

include/configs/sandbox.h

@@ -172,6 +172,7 @@
 #define CONFIG_CONSOLE_MUX
 #define CONFIG_SYS_CONSOLE_IS_IN_ENV
 #define LCD_BPP			LCD_COLOR16
+#define CONFIG_LCD_BMP_RLE8
 
 #define CONFIG_CROS_EC_KEYB
 #define CONFIG_KEYBOARD