net: freescale: ucc_geth: remove unused SKB_ALLOC_TIMEOUT

This was added in commit ce973b14 ("[PATCH] Freescale QE UCC gigabit
ethernet driver") but doesn't appear to have been used. Remove it now.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Link: https://lore.kernel.org/r/20201130001010.28998-1-chris.packham@alliedtelesis.co.nz


Signed-off-by: Jakub Kicinski <kuba@kernel.org>