cnss-utils: Compile firmware service file independently

Wlan firmware service file need to compile independently and
linked to other modules to avoid error of compiling same file
twice.

Change-Id: I1900940225c0c8a66b4cc9d8315d5800c7577e6a
Signed-off-by: Naman Padhiar <npadhiar@codeaurora.org>