ice: rename verify_cached to has_ready_bitmap

The tx->verify_cached flag is used to inform the Tx timestamp tracking
code whether it needs to verify the cached Tx timestamp value against
a previous captured value. This is necessary on E810 hardware which does
not have a Tx timestamp ready bitmap.

In addition, we currently rely on the fact that the
ice_get_phy_tx_tstamp_ready() function returns all 1s for E810 hardware.
Instead of introducing a brand new flag, rename and verify_cached to
has_ready_bitmap, inverting the relevant checks.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Karol Kolacinski <karol.kolacinski@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>