DO NOT MERGE A security fix to check buffer length in l2c_lcc_proc_pdu

Add check to make sure that data buffer is big enough to read the 2
bytes for length.

Also, fix a regression from the previous CL that checks the buffer length
before doing a memcpy. The previous check is too strict causing valid
sized buffers to be rejected. The length check is incorrect and off by the header size.

Bug: 120665616
Test: Run the SL4A Test for LE CoC, BleCoCTest
Merged-In: I30b7a8af11d3a5f974cb39e06b0e3463bebc8e9a
Change-Id: I30b7a8af11d3a5f974cb39e06b0e3463bebc8e9a
(cherry picked from commit 3deb5ec3)
(cherry picked from commit 5cab7c92)
(cherry picked from commit 401f39f0)