drivers/net/e1000.c: Cleanup whitespace

The patch removes unnecessary whitespace to fix checkpatch's
warning: unnecessary whitespace before a quoted newline

Signed-off-by: Minghuan Lian <Minghuan.Lian@freescale.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: York Sun <yorksun@freescale.com>