msm: camera_v2: remove gcc invocations

Remove gcc invocations, so that we can move to pure clang compilation.

Resolves:
make CC=clang HOSTCC=clang mrproper
...
Android GCC has been deprecated in favor of Clang, and will be removed from
Android in 2020-01 as per the deprecation plan in:
https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/+/master/GCC_4_9_DEPRECATION.md



Issue: FP3-A11#330
Bug: 141693040
Change-Id: I10557fb29b4a5d4139d690661c22ab5be3fedaaf
Signed-off-by: Petri Gynther <pgynther@google.com>