net: pasemi: remove set but not used variable 'cpyhdr'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/net/ethernet/pasemi/pasemi_mac.c: In function 'pasemi_mac_queue_csdesc':
drivers/net/ethernet/pasemi/pasemi_mac.c:1358:29: warning: variable 'cpyhdr' set but not used [-Wunused-but-set-variable]

It's never used since commit 8d636d8b ("pasemi_mac: jumbo
frame support") and can be removed.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>