lcd: mpc8xx: move mpc823-specific fb_put_byte to mpc8xx_lcd.c

Reduce the amount of platform-specific code in common/lcd.c by moving MPC823
implementation of fb_put_byte() to mpc8xx_lcd.c. Since we must also have a
default implementation for everybody else, make the remainder of the code
into a weak function.

Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Bo Shen <voice.shen@atmel.com>
Tested-by: Josh Wu <josh.wu@atmel.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Anatolij Gustschin <agust@denx.de>
diff --git a/common/lcd.c b/common/lcd.c
index f17b35b..efd9a87 100644
--- a/common/lcd.c
+++ b/common/lcd.c
@@ -635,11 +635,10 @@
 }
 #endif
 
-#if defined(CONFIG_MPC823)
-#define FB_PUT_BYTE(fb, from) *(fb)++ = (255 - *(from)++)
-#else
-#define FB_PUT_BYTE(fb, from) *(fb)++ = *(from)++
-#endif
+__weak void fb_put_byte(uchar **fb, uchar **from)
+{
+	*(*fb)++ = *(*from)++;
+}
 
 #if defined(CONFIG_BMP_16BPP)
 __weak void fb_put_word(uchar **fb, uchar **from)
@@ -764,7 +763,7 @@
 			WATCHDOG_RESET();
 			for (j = 0; j < width; j++) {
 				if (bpix != 16) {
-					FB_PUT_BYTE(fb, bmap);
+					fb_put_byte(&fb, &bmap);
 				} else {
 					*(uint16_t *)fb = cmap_base[*(bmap++)];
 					fb += sizeof(uint16_t) / sizeof(*fb);