drm/xe: Make xe_mmio_read|write() functions non-inline

drm/xe: Make xe_mmio_read|write() functions non-inline

Shortly we will updating xe_mmio_read|write() functions with SR-IOV
specific features making those functions less suitable for inline.
Convert now those functions into regular ones, lowering driver
footprint, according to scripts/bloat-o-meter, by 6%

add/remove: 18/18 grow/shrink: 31/603 up/down: 2719/-79663 (-76944)
Function                                     old     new   delta
Total: Before=1276633, After=1199689, chg -6.03%
add/remove: 0/0 grow/shrink: 0/0 up/down: 0/0 (0)
Data                                         old     new   delta
Total: Before=48990, After=48990, chg +0.00%
add/remove: 0/0 grow/shrink: 0/0 up/down: 0/0 (0)
RO Data                                      old     new   delta
Total: Before=115680, After=115680, chg +0.00%

Reviewed-by: Matt Roper <[email protected]>
Signed-off-by: Michal Wajdeczko <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Michał Winiarski <[email protected]>