Remove unnecessary quoting from twres path

The C flag defines already use -DVAR=\"..\", so stripping these extra quotes
should not affect those defines.

The makefile does not need the quoting at all.

Makefile example output...
before: mkdir -p (omitted)/recovery/root"/twres/"
after:  mkdir -p (omitted)/recovery/root/twres/

Change-Id: I8f557662eb18b5ea40b63bc055d12be4440251e6