ARM: configs: qcom_defconfig: Reduce CMA size to 64MB

Not all platforms are able to allocate CMA size of 256MB. One such
platform is SDX55. Hence, use the standard 64MB size for CMA.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20210408170930.91834-8-manivannan.sadhasivam@linaro.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>