init/service.cpp: fix FD leak for services with consoles

When init starts a service with a console, it tests for the presence of
a readable/writable console device. The test results in a leaked file
descriptor.

Use access() instead of open() to avoid leaking file descriptors.

Bug introduced in 70daa670.

Test: compiles and device boots
Change-Id: I4efcfa0bb2cdb09f0455bc04a3a91e784bda7962