Revert "config_deviceHardwareKeys: the correct default is 0"

the correct default is the default default.

Device trees with 0 hardware keys will set it as such thusly, and ones with 15 may not.
don't mess wiv it

This reverts commit aad2277a99e123e3ae88a2632b0ffdc78c774aea.

Change-Id: I4596436bc9b827a9bbf211e2d6593789ba685ca8