ARM: rpi: rename rpi_b to rpi

The U-Boot port runs on a variety of RPi models, not just the B. So,
rename the port to something slightly more generic.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
diff --git a/common/lcd.c b/common/lcd.c
index 28b3fe7..3ed504d 100644
--- a/common/lcd.c
+++ b/common/lcd.c
@@ -530,7 +530,7 @@
 	lcd_ctrl_init(lcdbase);
 
 	/*
-	 * lcd_ctrl_init() of some drivers (i.e. bcm2835 on rpi_b) ignores
+	 * lcd_ctrl_init() of some drivers (i.e. bcm2835 on rpi) ignores
 	 * the 'lcdbase' argument and uses custom lcd base address
 	 * by setting up gd->fb_base. Check for this condition and fixup
 	 * 'lcd_base' address.