qca: move ARM specific files to another sublevel

As the U-boot source is going to be common between ARM and MIPS
architecture , it is required to pick only the files specific
to the respective architectures during the build.

So, move the qca arm target specific common files to another
sub level by specifying the ARCH arm.

Change-Id: I06b538834109981f21fef6270bfb8e437a2f5a7e
Signed-off-by: Prabhu Jayakumar <pjayak@codeaurora.org>
64 files changed