platform/x86: ideapad-laptop: Disable touchpad_switch for ELAN0634

Newer ideapads (e.g.: Yoga 14s, 720S 14) come with ELAN0634 touchpad do not
use EC to switch touchpad.

Reading VPCCMD_R_TOUCHPAD will return zero thus touchpad may be blocked
unexpectedly.
Writing VPCCMD_W_TOUCHPAD may cause a spurious key press.

Add has_touchpad_switch to workaround these machines.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: stable@vger.kernel.org # 5.4+
--
v2: Specify touchpad to ELAN0634
v3: Stupid missing ! in v2
v4: Correct acpi_dev_present usage (Hans)
Link: https://lore.kernel.org/r/20210107144438.12605-1-jiaxun.yang@flygoat.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>