[intel] Convert relocations to not be cleared out on buffer submit.

[intel] Convert relocations to not be cleared out on buffer submit.

We have two consumers of relocations.  One is static state buffers, which
want the same relocation every time.  The other is the batchbuffer, which gets
thrown out immediately after submit.  This lets us reduce repeated computation
for static state buffers, and clean up the code by moving relocations nearer
to where the state buffer is computed.