drm/xe: Use LRC prefix rather than CTX prefix in lrc desc defines

drm/xe: Use LRC prefix rather than CTX prefix in lrc desc defines

The sparc build fails [1] due to CTX_VALID being redefined. Fix this by
using a better naming convention of LRC_VALID as this define is used in
setting bits in the lrc descriptor. To be uniform, change other define
with LRC prefix too.

[1] https://lore.kernel.org/all/20240123111235.3097079-1-geert@linux-m68k.org/

v2:
- s/LEGACY_64B_CONTEXT/LRC_LEGACY_64B_CONTEXT (Lucas)

Fixes: 0bc519d20ffa ("drm/xe: Remove GEN[0-9]*_ prefixes")
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240123212638.1605626-1-matthew.brost@intel.com