drivers: ethos_u: update dcache API for new HAL

Update ethosu_flush_dcache() and ethosu_invalidate_dcache() to accept
base_addr and base_addr_size arrays, with num_base_addr as the element
count, as required by the new Ethos-U driver. Add (uintptr_t) casts to
support 32-bit targets.

Signed-off-by: Johan Alfvén <johan.alfven@arm.com>