dma-buf: heaps: Clear CMA pages with clear_page()

dma-buf: heaps: Clear CMA pages with clear_page()

clear_page() translates into memset(*p, 0, PAGE_SIZE) on some
architectures, but on the major architectures it will call
an optimized assembly snippet so use this instead of open
coding a memset().

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Nirmoy Das <nirmoyd@nvidia.com>
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20251130-dma-buf-heap-clear-page-v1-1-a8dcea2a88ee@linaro.org