drm/xe/xe_migrate: Cast to output precision before multiplying operands

drm/xe/xe_migrate: Cast to output precision before multiplying operands

Addressing potential overflow in result of  multiplication of two lower
precision (u32) operands before widening it to higher precision
(u64).

-v2
Fix commit message and description. (Rodrigo)

Cc: Rodrigo Vivi <[email protected]>
Signed-off-by: Himal Prasad Ghimiray <[email protected]>
Reviewed-by: Rodrigo Vivi <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Rodrigo Vivi <[email protected]>
(cherry picked from commit 34820967ae7b45411f8f4f737c2d63b0c608e0d7)
Signed-off-by: Lucas De Marchi <[email protected]>