brcmfmac: update 43012 F2 watermark setting to fix DMA Error during UDP RX Traffic

The number of words that the read FIFO has to contain except
the end of frame before sends data back to the host.
Max watermark = (512B - 2* (BurstLength))/4 =
(512 - 128)/4 = 384/4 = 0x60
so if burst length (i.e. BurstLength = 64) is increased,
watermark has to be reduced. This is the optimal setting for this chip.

Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Naveen Gupta <naveen.gupta@cypress.com>
Signed-off-by: Chi-Hsien Lin <chi-hsien.lin@cypress.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>