target/riscv: Fix the element agnostic function problem

target/riscv: Fix the element agnostic function problem

In RVV and vcrypto instructions, the masked and tail elements are set to 1s
using vext_set_elems_1s function if the vma/vta bit is set. It is the element
agnostic policy.

However, this function can't deal the big endian situation. This patch fixes
the problem by adding handling of such case.

Signed-off-by: Huang Tao <eric.huang@linux.alibaba.com>
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Cc: qemu-stable <qemu-stable@nongnu.org>
Message-ID: <20240325021654.6594-1-eric.huang@linux.alibaba.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
(cherry picked from commit 75115d880c6d396f8a2d56aab8c12236d85a90e0)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>