ACPI: APEI: EINJ: Fix probe error message

ACPI: APEI: EINJ: Fix probe error message

Commit 6cb9441bfe8d ("ACPI: APEI: EINJ: Transition to the faux device
interface") updated the APEI error injection driver to use the faux
device interface and now for devices that don't support ACPI, the
following error message is seen on boot:

 ERR KERN faux acpi-einj: probe did not succeed, tearing down the device

The APEI error injection driver returns -ENODEV in the probe function
if ACPI is not supported and so after transitioning the driver to the
faux device interface, the error returned from the probe now causes the
above error message to be displayed.

Fix this by moving the code that detects if ACPI is supported to the
einj_init() function to fix the false error message displayed for
devices that don't support ACPI.

Fixes: 6cb9441bfe8d ("ACPI: APEI: EINJ: Transition to the faux device interface")
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://patch.msgid.link/20250501124621.1251450-1-jonathanh@nvidia.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>