net/ena/base: fix testing for supported hash function

net/ena/base: fix testing for supported hash function

There was a bug in ena_com_fill_hash_function(), which was causing bit to
be shifted left one bit too much.

To fix that, the ENA_FFS macro is being used (returning the location of
the first bit set), hash_function value is being subtracted by 1 if any
hash function is supported by the device and BIT macro is used for
shifting for better verbosity.

Fixes: 99ecfbf845b3 ("ena: import communication layer")
Cc: stable@dpdk.org
Signed-off-by: Michal Krawczyk <mk@semihalf.com>