riscv: mm: Fix incorrect ASID argument when flushing TLB

Currently, we pass the CONTEXTID instead of the ASID to the TLB flush
function. We should only take the ASID field to prevent from touching
the reserved bit field.

Fixes: 3f1e7829

 ("riscv: add ASID-based tlbflushing methods")
Signed-off-by: Dylan Jhong <dylan@andestech.com>
Reviewed-by: Sergey Matyukevich <sergey.matyukevich@syntacore.com>
Link: https://lore.kernel.org/r/20230313034906.2401730-1-dylan@andestech.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>