HID: intel-thc-hid: intel-thc: Fix incorrect pointer arithmetic in I2C regs save

In the Linux kernel, the following vulnerability has been resolved:

HID: intel-thc-hid: intel-thc: Fix incorrect pointer arithmetic in I2C regs save

Improper use of secondary pointer (&dev->i2c_subip_regs) caused
kernel crash and out-of-bounds error:

BUG: KASAN: slab-out-of-bounds in _regmap_bulk_read+0x449/0x510
Write of size 4 at addr ffff888136005dc0 by task kworker/u33:5/5107

CPU: 3 UID: 0 PID: 5107 Comm: kworker/u33:5 Not tainted 6.16.0+ #3 PREEMPT(voluntary)
Workqueue: async async_run_entry_fn
Call Trace:
<TASK>
dump_stack_lvl+0x76/0xa0
print_report+0xd1/0x660
? __pfx__raw_spin_lock_irqsave+0x10/0x10
? kasan_complete_mode_report_info+0x26/0x200
kasan_report+0xe1/0x120
? _regmap_bulk_read+0x449/0x510
? _regmap_bulk_read+0x449/0x510
__asan_report_store4_noabort+0x17/0x30
_regmap_bulk_read+0x449/0x510
? __pfx__regmap_bulk_read+0x10/0x10
regmap_bulk_read+0x270/0x3d0
pio_complete+0x1ee/0x2c0 [intel_thc]
? __pfx_pio_complete+0x10/0x10 [intel_thc]
? __pfx_pio_wait+0x10/0x10 [intel_thc]
? regmap_update_bits_base+0x13b/0x1f0
thc_i2c_subip_pio_read+0x117/0x270 [intel_thc]
thc_i2c_subip_regs_save+0xc2/0x140 [intel_thc]
? __pfx_thc_i2c_subip_regs_save+0x10/0x10 [intel_thc]
[...]
The buggy address belongs to the object at ffff888136005d00
which belongs to the cache kmalloc-rnd-12-192 of size 192
The buggy address is located 0 bytes to the right of
allocated 192-byte region [ffff888136005d00, ffff888136005dc0)

Replaced with direct array indexing (&dev->i2c_subip_regs[i]) to ensure
safe memory access.