sfc: Increase size of RX SKB header area
sfc: Increase size of RX SKB header area

This allows the SKB to hold the headers without reallocation more often.

Signed-off-by: Ben Hutchings <0672176982fbc629cc374f31a7a45ae1671abf90@solarflare.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs