riscv: Enable CMA support

stable inclusion
from stable-v5.10.155
commit d7716240bca508fb9e74d00d96304bc30acc3d6c
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7M5F4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d7716240bca508fb9e74d00d96304bc30acc3d6c



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[ Upstream commit da815582 ]

riscv has selected HAVE_DMA_CONTIGUOUS, but doesn't call
dma_contiguous_reserve().  This calls dma_contiguous_reserve(), which
enables CMA.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Stable-dep-of: 50e63dd8 ("riscv: fix reserved memory setup")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>