common/sfc_efx/base: fix MAE match spec validation helper

common/sfc_efx/base: fix MAE match spec validation helper

A particular FW version is aware of some set of match fields.
Depending on FW configuration and match specification type, a
known field may not necessarily be allowed to have a non-zero
mask. FW communicates such restrictions via field capabilities
MCDI. Newer FW may be aware of more fields. For such fields,
older FW simply does not report any capabilities.

A situation may occur when libefx is aware of a match field
which the FW is unaware of (eg., older FW), that is, FW does
not report capability status for this field. In this case,
libefx must consider such field as unsupported and demand
all-zeros mask for it when validating match specifications.

Currently, the helper in question simply exits and reports
that the specification is valid when it encounters a field
with no capability status available. This is clearly wrong.

Introduce the missing check to fix the problem.

Fixes: 34285fd0891d ("common/sfc_efx/base: add match spec validate API")
Cc: stable@dpdk.org
Reviewed-by: Andy Moreton <amoreton@xilinx.com>
Reviewed-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>