drm/xe/uc: Use u64 for offsets for which we use upper_32_bits()

drm/xe/uc: Use u64 for offsets for which we use upper_32_bits()

The GGTT is currently a 32 bit address space, but the HW and GuC
support 48b addresses in GGTT-related operations, both to keep the
interface/HW paths common between PPGTT and GGTT and to allow for
future increase of the GGTT size.
This leaves us having to program a 64b field with a 32b offset, which
currently we're in some cases doing this by using an upper_32_bits()
call on a 32b variable, which doesn't make any sense. To do this cleanly
we have 2 options:

1 - Set the upper 32 bits directly to zero.
2 - Use 64b variables for the offset and keep programming the whole thing,
    so we're ready if we ever have bigger offsets.

This patch goes with option #2 and switches the related variables to u64.

v2: don't change the log ctl flag variable (John)

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240319195101.2784480-1-daniele.ceraolospurio@intel.com