linux-yocto/u-boot-lsi: Update SRCREV to tags  7.8.1.14 and 5.8.1.21

Signed-off-by: Paul Butler <paul.butler@windriver.com>
linux-yocto: Specify LINUX_KERNEL_TYPE for custom Kernel

For linux-yocto-custom standard and preempt-rt receipes explicit
specify the Kernel type using LINUX_KERNEL_TYPE variable.

Signed-off-by: Paul Butler <paul.butler@windriver.com>
core-image-large: Add receipe for rootfs image type

Add receipe for for core-image-large ROOTFS type and related
packagegroup receipe: packagegroup-core-large-boot.bb

Signed-off-by: Niraj Desai <nirajvdesai@gmail.com>
axm5500: Changed baurate to 9600 for ttyAMA0

For axm55xx machine change serial console baurate for ttyAMA0 from
115200 to 9600.
linux-yocto/u-boot-lsi: Update SRCREV to tags 7.8.1.17 and u-boot to 5.8.1.24

Signed-off-by: Paul Butler <paul.butler@windriver.com>