ice: Fix DSCP PFC TLV creation

When creating the TLV to send to the FW for configuring DSCP mode PFC,the
PFCENABLE field was being masked with a 4 bit mask (0xF), but this is an 8
bit bitmask for enabled classes for PFC.  This means that traffic classes
4-7 could not be enabled for PFC.

Remove the mask completely, as it is not necessary, as we are assigning 8
bits to an 8 bit field.

Fixes: 2a87bd73 ("ice: Add DSCP support")
Signed-off-by: Dave Ertman <david.m.ertman@intel.com>
Signed-off-by: Karen Ostrowska <karen.ostrowska@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>