net: danipc: Increase mtu and fifo size for danipc

Change MTU and descriptor size from 128 to 1600 bytes to move
data more efficiently between Krait and Hex2 processors. Get the
fifo size from dt.

Change-Id: Id75f058c54b334389323dbfe199c2f406d57c282
Acked-by: Xiuping Lu <xiupingl@qti.qualcomm.com>
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>