[RISCV][MCA] Remove unnecessary -debug flag from test (NFC)

This test doesn't appear to actually use -debug output, and the
flag makes the test fail on non-assert builds.

Author: nikic

llvm/test/tools/llvm-mca/RISCV/SiFive7/strided-load-x0.s

@@ -1,5 +1,5 @@
 # NOTE: Assertions have been autogenerated by utils/update_mca_test_checks.py
-# RUN: llvm-mca -debug -mtriple=riscv64 -mcpu=sifive-x280 -iterations=1 < %s | FileCheck %s
+# RUN: llvm-mca -mtriple=riscv64 -mcpu=sifive-x280 -iterations=1 < %s | FileCheck %s
 
 vsetvli zero, zero, e32, m1, tu, mu