ice: fix 'adjust' timer programming for E830 devices

ice: fix 'adjust' timer programming for E830 devices

Fix incorrect 'adjust the timer' programming sequence for E830 devices
series. Only shadow registers GLTSYN_SHADJ were programmed in the
current implementation. According to the specification [1], write to
command GLTSYN_CMD register is also required with CMD field set to
"Adjust the Time" value, for the timer adjustment to take the effect.

The flow was broken for the adjustment less than S32_MAX/MIN range
(around +/- 2 seconds). For bigger adjustment, non-atomic programming
flow is used, involving set timer programming. Non-atomic flow is
implemented correctly.

Testing hints:
Run command:
	phc_ctl /dev/ptpX get adj 2 get
Expected result:
	Returned timestamps differ at least by 2 seconds

[1] Intel® Ethernet Controller E830 Datasheet rev 1.3, chapter 9.7.5.4
https://cdrdv2.intel.com/v1/dl/getContent/787353?explicitVersion=true

Fixes: f00307522786 ("ice: Implement PTP support for E830 devices")
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Grzegorz Nitka <grzegorz.nitka@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Rinitha S <sx.rinitha@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260416-iwl-net-submission-2026-04-14-v2-1-686c33c9828d@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>