net: nfs: remove superfluous conversions

rpc_pkt.u.call.data is an array of uint32_t. There is no need to convert
it to uint32_t *.

memcpy() expects void * as it 1st and 2nd argument. There is no point in
converting pointers to char * before passing them to memcpy().

In ntohl(data[1]) != 0 calling ntohl() is superfluous. If the value is
zero, does not depend on the byte order.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>