ACPI: EC: Relax sanity check of the ECDT ID string

ACPI: EC: Relax sanity check of the ECDT ID string

It turns out that the ECDT table inside the ThinkBook 14 G7 IML
contains a valid EC description but an invalid ID string
("_SB.PC00.LPCB.EC0"). Ignoring this ECDT based on the invalid
ID string prevents the kernel from detecting the built-in touchpad,
so relax the sanity check of the ID string and only reject ECDTs
with empty ID strings.

Reported-by: Ilya K <me@0upti.me>
Fixes: 7a0d59f6a913 ("ACPI: EC: Ignore ECDT tables with an invalid ID string")
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Tested-by: Ilya K <me@0upti.me>
Link: https://patch.msgid.link/20250729062038.303734-1-W_Armin@gmx.de
Cc: 6.16+ <stable@vger.kernel.org> # 6.16+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>