Map CESA SRAM memory in driver attach for Armada38x

On other platforms with CESA accelerator the SRAM memory is mapped in
early init before driver is attached. This method only works correctly
with mappings no smaller than L1 section size (1MB). There may be more
SRAM blocks and they may have smaller sizes than 1MB as is the case
for Armada38x. Instead, map SRAM memory with bus_space_map() in CESA
driver attach. Note that we can no longer assume that VA == PA for the
SRAM.

Submitted by: Michal Stanek <mst@semihalf.com
Obtained from: Semihalf
Sponsored by: Stormshield
Differential revision: https://reviews.freebsd.org/D6215