net/wan/fsl_ucc_hdlc: fix out of bounds write on array utdm_info

Array utdm_info is declared as an array of MAX_HDLC_NUM (4) elements
however up to UCC_MAX_NUM (8) elements are potentially being written
to it.  Currently we have an array out-of-bounds write error on the
last 4 elements. Fix this by making utdm_info UCC_MAX_NUM elements in
size.

Addresses-Coverity: ("Out-of-bounds write")
Fixes: c19b6d24 ("drivers/net: support hdlc function for QE-UCC")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>