touchschreen/focaltech_flash: Refactor and simplify chipid check

LLVM reported build issue with existing chip id check as
it gets confused with the if blocks. Refactor and simplify
chipid check to fix the error.

Change-Id: Idda7d239a369be2c52b2b2ef040332b701705865
Signed-off-by: Shiraz Hashim <shashim@codeaurora.org>