Fix: armasm debug information missing for debug builds

The build system failed to properly specify compilation switches for
armasm when executing debug builds (-DCMAKE_BUILD_TYPE=Debug).
As a resolution the "embedded_project_fixup()" processing was changed
to define proper compilation switches.

Change-Id: I412be8dc3037df860f064e32c4cad2c48c70a30e
Signed-off-by: Gyorgy Szing <Gyorgy.Szing@arm.com>