[PASEMI_MAC]: remove unused function

drivers/net/pasemi_mac.c: At top level:
drivers/net/pasemi_mac.c:89: warning: 'read_iob_reg' defined but not used

Signed-off-by: Satyam Sharma <satyam@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>