UPSTREAM: arm64: remove the unnecessary arm64_swiotlb_init()

The commit 3690951f
(arm64: Use swiotlb late initialisation)
switches the DMA mapping code to swiotlb_tlb_late_init_with_default_size(),
the arm64_swiotlb_init() will not used anymore, so remove this function.

Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

(cherry picked from commit eb8a653137b7e74f7cdc01f814eb9d094a65aed9)
Signed-off-by: Tomasz Figa <tfiga@chromium.org>

Bug: 24475017

Change-Id: Ida77712c3601e2b213a4f3f913e25fba184153d7
Signed-off-by: Kees Cook <keescook@google.com>