brcmfmac: 43012 Update MES Watermark

Set MES watermark size to 0x50 for 43012. It fixes SDIO bus hang issue
when running at high throughput.

Signed-off-by: Double Lo <double.lo@cypress.com>
Signed-off-by: Chi-hsien Lin <chi-hsien.lin@cypress.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200529034938.124533-6-chi-hsien.lin@cypress.com