It is a good practice to use BIT() instead of (1 << x).
Replace the current usages with BIT().

Take this opportunity to replace few (1UL << x) with BIT() as well
for consistency.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20240420151741.962500-5-atishp@rivosinc.comSigned-off-by: Anup Patel <anup@brainfault.org>