rpi-firmware: modify settings for Pi 2

Remove low-level settings from config.txt like arm_freq and sdram_freq.
The defaults should be good for most and differ by Pi model.
E.g. the Pi 2 runs at 900 Mhz by default, setting arm_freq=700
like we had previously would underclock it.

Add short description in comments to options.
Mention initramfs option.

Remove obsolete options from cmdline.txt

Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/rpi-firmware/cmdline.txt

@@ -1 +1 @@
-dwc_otg.fiq_fix_enable=1 sdhci-bcm2708.sync_after_dma=0 dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootwait
+root=/dev/mmcblk0p2 rootwait

package/rpi-firmware/config.txt

@@ -4,11 +4,17 @@
 # See http://buildroot.org/downloads/manual/manual.html#rootfs-custom
 # and http://elinux.org/RPiconfig for a description of config.txt syntax
 
-arm_freq=700
-core_freq=250
 kernel=zImage
+
+# To use an external initramfs file
+#initramfs rootfs.cpio.gz
+
+# Disable overscan assuming the display supports displaying the full resolution
+# If the text shown on the screen disappears off the edge, comment this out
 disable_overscan=1
+
+# How much memory in MB to assign to the GPU on Pi models having
+# 256, 512 or 1024 MB total memory
 gpu_mem_256=100
 gpu_mem_512=100
-sdram_freq=400
-over_voltage=0
+gpu_mem_1024=100