MAINTAINERS: Update pattern for qcom_scm

Update pattern for qcom_scm, so that get_maintainer.pl will show the
correct maintainers + lists, not only for qcom_scm.c, but also for
the files: qcom_scm-32.c, qcom_scm-64.c, qcom_scm.h.

Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>