ARMV7: OMAP: Add mpurate boot arg for Overo and Beagle

Allows one to set the processor clock rate via "setenv mpurate 720" for example

Default is set to a "safe" 500 Mhz.
Signed-off-by: NSteve Sakoman <steve@sakoman.com>
Signed-off-by: NSandeep Paulraj <s-paulraj@ti.com>

include/configs/omap3_beagle.h

@@ -183,6 +183,7 @@
 	"loadaddr=0x82000000\0" \
 	"usbtty=cdc_acm\0" \
 	"console=ttyS2,115200n8\0" \
+	"mpurate=500\0" \
 	"vram=12M\0" \
 	"dvimode=1024x768MR-16@60\0" \
 	"defaultdisplay=dvi\0" \
@@ -191,6 +192,7 @@
 	"nandroot=/dev/mtdblock4 rw\0" \
 	"nandrootfstype=jffs2\0" \
 	"mmcargs=setenv bootargs console=${console} " \
+		"mpurate=${mpurate} " \
 		"vram=${vram} " \
 		"omapfb.mode=dvi:${dvimode} " \
 		"omapfb.debug=y " \
@@ -198,6 +200,7 @@
 		"root=${mmcroot} " \
 		"rootfstype=${mmcrootfstype}\0" \
 	"nandargs=setenv bootargs console=${console} " \
+		"mpurate=${mpurate} " \
 		"vram=${vram} " \
 		"omapfb.mode=dvi:${dvimode} " \
 		"omapfb.debug=y " \

include/configs/omap3_overo.h

@@ -153,6 +153,7 @@
 #define CONFIG_EXTRA_ENV_SETTINGS \
 	"loadaddr=0x82000000\0" \
 	"console=ttyS2,115200n8\0" \
+	"mpurate=500\0" \
 	"vram=12M\0" \
 	"dvimode=1024x768MR-16@60\0" \
 	"defaultdisplay=dvi\0" \
@@ -161,6 +162,7 @@
 	"nandroot=/dev/mtdblock4 rw\0" \
 	"nandrootfstype=jffs2\0" \
 	"mmcargs=setenv bootargs console=${console} " \
+		"mpurate=${mpurate} " \
 		"vram=${vram} " \
 		"omapfb.mode=dvi:${dvimode} " \
 		"omapfb.debug=y " \
@@ -168,6 +170,7 @@
 		"root=${mmcroot} " \
 		"rootfstype=${mmcrootfstype}\0" \
 	"nandargs=setenv bootargs console=${console} " \
+		"mpurate=${mpurate} " \
 		"vram=${vram} " \
 		"omapfb.mode=dvi:${dvimode} " \
 		"omapfb.debug=y " \