The dcache.cva encoding shown in the comments are wrong, it's for
dcache.cval1 (which is restricted to L1) instead.

Fix this in the comment and in the hardcoded instruction.
Signed-off-by: Icenowy Zheng <uwu@icenowy.me>
Tested-by: Sergey Matyukevich <sergey.matyukevich@syntacore.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Guo Ren <guoren@kernel.org>
Tested-by: Drew Fustini <dfustini@baylibre.com>
Link: https://lore.kernel.org/r/20230912072410.2481-1-jszhang@kernel.orgSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>