ice: initialize local variable 'tlv'

Clang static analysis reports this issues
ice_common.c:5008:21: warning: The left expression of the compound
  assignment is an uninitialized value. The computed value will
  also be garbage
  ldo->phy_type_low |= ((u64)buf << (i * 16));
  ~~~~~~~~~~~~~~~~~ ^

When called from ice_cfg_phy_fec() ldo is the uninitialized local
variable tlv.  So initialize.

Fixes: ea78ce4d

 ("ice: add link lenient and default override support")
Signed-off-by: Tom Rix <trix@redhat.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>