xtensa: ISS: improve simcall assembly

Drop redundant result moving from inline assembly, use a1 and b1 values
as return value and errno value respectively.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
This commit is contained in:
Max Filippov 2020-02-04 12:51:21 -08:00
commit c74c0fd228