staging: et131x: Remove redundant check and return statement

In nic_send_packet(), by the time 'frag' is checked to be zero, it never
is - the for loop has been entered (as nr_frags is always > 0) and frag
has been incremented at least once. Remove the check and associated
error return.

Signed-off-by: Mark Einon <mark.einon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>