firmware: qcom: scm: fix compilation error when disabled

firmware: qcom: scm: fix compilation error when disabled

BugLink: https://bugs.launchpad.net/bugs/1857158
[ Upstream commit 16ad9501b1f2edebe24f8cf3c09da0695871986b ]

This fixes the case when CONFIG_QCOM_SCM is not enabled, and linux/errno.h
has not been included previously.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>