Anlogic FPGAs all have two kinds of BRAMs, one is 9bit*1K when being
true dual port (or 18bit*512 when simple dual port), the other is
16bit*2K.
Supports mapping of these two kinds of BRAMs. 9Kbit BRAM in SDP mode and
32Kbit BRAM with 8bit width are not support yet.
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>