sunxi: mali: Fix UMP on systems with 2 GiB of RAM (phys->bus issue)

The mali driver has some code for converting between physical addresses
and bus addresses (they call them "cpu physical addresses" and "physical
addresses" respectively). For OS memory allocation, this delta is configured
in the "cpu_usage_adjust" variable, as can be seen in the mali driver code.

But in addition to OS memory allocation, mali also handles external memory
wrapping and UMP memory wrapping. The physical/bus addresses translation
is done separately for each type of memory in the mali driver. The older
commit from Huang Benn updated the mali code to do physical->bus addresses
translation for OS memory and external memory, but did not address a
similar issue with UMP memory. Incorrectly working UMP results in black
windows for EGL/GLES applications (and also in memory corruption) on
the systems with 2 GiB of RAM when used with X11 mali drivers:
    https://github.com/ssvb/xf86-video-fbturbo/issues/27

This patch tries to do the physical->bus addresses translation for
both external and UMP memory a bit lower in the call chain (in the
"mali_allocation_engine_map_physical" function). That's just because
the old "uk_args.phys_addr = __phys_to_bus(uk_args.phys_addr)" code
does not look nice (the "phys_addr" variable name becomes somewhat
misleading and ambiguous).

Signed-off-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>