soc: qcom: Drop help text for QCOM_QMI_HELPERS

The help text is visible in menuconfig, however QCOM_QMI_HELPERS is a
hidden kconfig, so it is not selectable in menuconfig.

Remove the help text so that it is more clear that this is intentionally
a hidden kconfig.

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