habanalabs: change mmu_get_real_page_size to be ASIC-specific

This patch breaks the cumbersome implementation of "get real page size"
along with it's multiple inner conditions and implement each case
(according to the real complexity) inside an ASIC function.

Signed-off-by: Ohad Sharabi <osharabi@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>