firmware: qcom: scm: request the waitqueue irq *after* initializing SCM

firmware: qcom: scm: request the waitqueue irq *after* initializing SCM

There's a subtle race in the SCM driver: we assign the __scm pointer
before requesting the waitqueue interrupt. Assigning __scm marks the SCM
API as ready to accept calls. It's possible that a user makes a call
right after we set __scm and the firmware raises an interrupt before the
driver's ready to service it. Move the __scm assignment after we request
the interrupt.

This has the added benefit of allowing us to drop the goto label.

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20250630-qcom-scm-race-v2-4-fa3851c98611@linaro.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>