riscv: KVM: Fix hart suspend_type use

riscv: KVM: Fix hart suspend_type use

The spec says suspend_type is 32 bits wide and "In case the data is
defined as 32bit wide, higher privilege software must ensure that it
only uses 32 bit data." Mask off upper bits of suspend_type before
using it.

Fixes: 763c8bed8c05 ("RISC-V: KVM: Implement SBI HSM suspend call")
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20250217084506.18763-9-ajones@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>