soc: qcom: smem: Switch to EXPORT_SYMBOL_GPL()

SMEM has been GPL licensed from the start, and there is no reason to use
EXPORT_SYMBOL() so switch to the GPL version.

Signed-off-by: Robert Marko <robimarko@gmail.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Trilok Soni <quic_tsoni@quicinc.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230526204802.3081168-2-robimarko@gmail.com