ARM: qcom_defconfig: Fix MDM9515 LCC and GCC config

Correct prefix is MDM instead of MSM.

Fixes: 8aa788d3

 ("ARM: configs: qualcomm: Add MDM9615 missing defconfigs")
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>