linux-yocto: Add functions for building POWERPC DTB and FIT images

Create additional functions to append do_compile and do_deploy tasks
for kernel, function that will build the dtb, create fit images and
install them for multiple POWERPC targets:
- acp25xx
- acp342x
- acp344x
- ACP344xV2
- acp35xx

Signed-off-by: Paul Butler <paul.butler@windriver.com>
linux-yocto: Add support for building from YOCTO and GITHUB private repo

- Add support for building also from YOCTO repos and from the tip of
the LSI GitHub private repo depending what .inc files is included.
This choice is made by setting the LSI_SRC variable in the build's
local.conf file.
- Add FIT support files to SRC_URI for preempt-rt kernels.

Signed-off-by: Paul Butler <paul.butler@windriver.com>
linux-yocto: Add support for building from GITHUB public repo

- Add support for building also from the LSI GitHub public repo depending
what .inc files is included. This choice is done by setting the LSI_SRC
variable in the build's local.conf file.
- By default, with LSI_SRC not set in local.conf, the Kernel will be
fetched from YOCTO repos. This is done because LSI_SRC is set to
"linux-yocto" in receipes. local.conf will overwrite it.
LSI_SRC ?= "linux-yocto"

Signed-off-by: Paul Butler <paul.butler@windriver.com>
u-boot-lsi: Update SRCREV to tag to 5.8.1.44 and 4.8.1.91

- Update SRCREV to tag to 5.8.1.44 for lsi-v2013.01.01 branch
- Update SRCREV to tag to 4.8.1.91 for lsi-v2010.03 branch
- Set default UBOOT_SUFFIX to "img"

Signed-off-by: Paul Butler <paul.butler@windriver.com>
linux-yocto: Add support for building ARM DTB and FIT images

- Modify functions that build dtb, create fit images
  and install them also for ARM targets:
for 3.4:
  - axm55xx
  - axm55xxemu and axm55xxemu7
  - axm55xxsim16 and axm55xxsim
  - axm-ve-tc1 and axm-ve-tc2
for 3.10:
  - axm5504-emu and axm5504-sim
  - axm5507-emu
  - axm5516-amarillo and axm5516-sim
  - axm55xxemu7

- Specify the kernel version in receipes by setting KV variable

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