[ARM] 5067/1: _raw_write_can_lock macro bugfix

The current __raw_write_can_lock macro tests whether the lock can be
locked by checking if it is equal to 0x80000000, whereas the lock
should be lockable if its value is 0 i.e. unlocked state is
represented by 0. Hence the macro should test the value of lock
against 0 and not 0x80000000.

Signed-off-by: Surinder Pal Singh <srplsnh@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>