ice: check the return of ice_ptp_gettimex64

ice: check the return of ice_ptp_gettimex64

Clang static analysis reports this issue
time64.h:69:50: warning: The left operand of '+'
  is a garbage value
  set_normalized_timespec64(&ts_delta, lhs.tv_sec + rhs.tv_sec,
                                       ~~~~~~~~~~ ^
In ice_ptp_adjtime_nonatomic(), the timespec64 variable 'now'
is set by ice_ptp_gettimex64().  This function can fail
with -EBUSY, so 'now' can have a gargbage value.
So check the return.

Fixes: 06c16d89d2cb ("ice: register 1588 PTP clock device object for E810 devices")
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>