drm/nouveau/gsp: Fix potential integer overflow on integer shifts

The left shift int 32 bit integer constants 1 is evaluated using 32 bit
arithmetic and then assigned to a 64 bit unsigned integer. In the case
where the shift is 32 or more this can lead to an overflow. Avoid this
by shifting using the BIT_ULL macro instead.

Fixes: 6c3ac7bc ("drm/nouveau/gsp: support deeper page tables in COPY_SERVER_RESERVED_PDES")
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250522131512.2768310-1-colin.i.king@gmail.com