common/btle_ll.c: Return error code instead of uninitialized value
common/btle_ll.c: Return error code instead of uninitialized value

The variable rv was being returned without being initialized.  Instead,
return EC_SUCCESS.

BUG=None
BRANCH=None
TEST=Build all boards successfully.

Change-Id: If37057b737e6419c1d5cc22215a7d76d920d1267
Signed-off-by: Martin Roth <79230511ccf79da3f7e9e82dbcc9c1ec2f734fa0@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/370664

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec