[BNX2]: Remove REG_WR_IND/REG_RD_IND macros.

The REG_WR_IND/REG_RD_IND macros are unnecessary and obfuscate the
code.  Many callers to these macros read and write shared memory from
the bp->shmem_base, so we add 2 similar functions that automatically
add the shared memory base.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>