qemu_ram_ptr_length: take ram_addr_t as arguments

qemu_ram_ptr_length should take ram_addr_t as argument rather than
target_phys_addr_t because is doing comparisons with RAMBlock addresses.

cpu_physical_memory_map should create a ram_addr_t address to pass to
qemu_ram_ptr_length from PhysPageDesc phys_offset.

Remove code after abort() in qemu_ram_ptr_length.

Changes in v2:

- handle 0 size in qemu_ram_ptr_length;

- rename addr1 to raddr;

- initialize raddr to ULONG_MAX.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
