drm/xe/uapi: Restore flags VM_BIND_FLAG_READONLY and VM_BIND_FLAG_IMMEDIATE

drm/xe/uapi: Restore flags VM_BIND_FLAG_READONLY and VM_BIND_FLAG_IMMEDIATE

The commit 84a1ed5e6756 ("drm/xe/uapi: Remove unused flags") is partially
reverted. At the time, flags not used by user space were removed during
cleanup. Some flags now needed by the compute runtime are brought back in
this commit:
- DRM_XE_VM_BIND_FLAG_READONLY is used to write protect kernel ISA thus
preventing accidental overwrites.
- DRM_XE_VM_BIND_FLAG_IMMEDIATE is used to trigger mapping at the time of
binding in order to prevent faulting at execution time.

The changes in the compute runtime are ready and approved, see link below.

v2: Include a link to the PR in the commit message (Matthew Brost)

v3: Update kernel doc and improve commit message (Lucas De Marchi)

Cc: Mateusz Jablonski <mateusz.jablonski@intel.com>
Cc: Michal Mrozek <michal.mrozek@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://github.com/intel/compute-runtime/pull/717
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240329124403.7-1-francois.dugast@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>