tools: fix redundant conditions in v8.gyp for riscv64 and loong64

The builtins conditions for riscv64 and loong64 both have the form
'v8_target_arch=="X" or v8_target_arch=="X"' which is redundant.
This was copied from the mips64/mips64el pattern (where the 'or' is
correct since those are two different architectures) when riscv64
and loong64 support were first added.

Simplify both to match the pattern used by ppc64, s390x, and other
single-variant architectures.

Signed-off-by: Jamie Magee <jamie.magee@gmail.com>
PR-URL: #62608
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <richard.lau@ibm.com>

Author: JamieMagee

tools/v8_gypfiles/v8.gyp

@@ -342,12 +342,12 @@
             '<(V8_ROOT)/src/builtins/arm64/builtins-arm64.cc',
           ],
         }],
-        ['v8_target_arch=="riscv64" or v8_target_arch=="riscv64"', {
+        ['v8_target_arch=="riscv64"', {
           'sources': [
             '<(V8_ROOT)/src/builtins/riscv/builtins-riscv.cc',
           ],
         }],
-        ['v8_target_arch=="loong64" or v8_target_arch=="loong64"', {
+        ['v8_target_arch=="loong64"', {
           'sources': [
             '<(V8_ROOT)/src/builtins/loong64/builtins-loong64.cc',
           ],