stdlib: Fix get_isa_from_str() exception behavior in isas.py

When given an input string that does not match any valid ISA, the
get_isa_from_str() function should call get_isas_str_set() to to print
the valid ISA strings in the exception. The current behavior is to
recursively call get_isa_from_str() with no input, which prevents
the correct exception from being raised. This change causes the
correct exception to be raised for invalid inputs.

Change-Id: I92bfe862bbd99ce0b63bfc124e539fab3b175e0c
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/65411
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>

src/python/gem5/isas.py

@@ -81,7 +81,7 @@ def get_isa_from_str(input: str) -> ISA:
             return isa
 
     valid_isas_str_list = str()
-    for isa_str in get_isa_from_str():
+    for isa_str in get_isas_str_set():
         valid_isas_str_list += f"{os.linesep}{isa_str}"
 
     raise Exception(