msm: Makefile.boot: Refresh list of dtb files to build

Several MSM .dts files have been added to the kernel tree, but
corresponding dtb Make targets were not added to Makefile.boot.
Add the missing entries.

Change-Id: I7c34dba8a5d90bda06b31ac26fe1682ea63432a0
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>