kexecboot-cfg: add new options for DTB and CMDLINE

Signed-off-by: Andrea Adami <andrea.adami@gmail.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-initramfs/recipes-bsp/kexecboot/kexecboot-cfg_0.2.bb

@@ -19,9 +19,15 @@ LABEL=${KEXECBOOT_LABEL}
 # Specify full kernel path on target.
 KERNEL=/boot/${KERNEL_IMAGETYPE}
 #
+# Specify which device tree blob to use
+# DTB=/boot/my-own-dtb
+#
 # Append this tags to the kernel cmdline.
 APPEND=${CMDLINE} ${CMDLINE_DEBUG}
 #
+# Overwrite kernel command line instead of appending to it
+# CMDLINE=console=/dev/tty0 root=/dev/sdb1
+#
 # Specify optional initrd/initramfs.
 # INITRD=/boot/initramfs.cpio.gz
 #