Correct MV_DDR_CADR_BASE definiton in mvwin.h

SOC_MV_ARMADAXP ifdef was enhanced with SOC_MV_ARMADA38X,
correcting MV_DDR_CADR_BASE definition. It fixes PCIe hangs issue.

Reviewed by: andrew
Obtained from: Semihalf
Sponsored by: Stormshield
Submitted by: Bartosz Szczepanek <bsz@semihalf.com>
Differential revision: https://reviews.freebsd.org/D4380