Remove toString methods in Vehicle HAL.

These methods are already generated by HIDL, but this is
only now being realized.

Test: methods no longer conflict
Merged-In: I522630267beb7f87713a0a54c1ecb38077dc1b4e
Change-Id: I522630267beb7f87713a0a54c1ecb38077dc1b4e
1 file changed