net/ice/base: fix null pointer dereferences for parser

net/ice/base: fix null pointer dereferences for parser

Null-checking "p" suggests that it may be null, but it has already
been dereferenced on all paths leading to the check. Thus correct
the code lines and remove the redundant line.

Fixes: c84f8aa2100c ("net/ice/base: add parser runtime skeleton")
Signed-off-by: Junfeng Guo <junfeng.guo@intel.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>