gdb/testsuite: Improve comments in recently added test

Remove the use of 'I' within some comments in a recently added test.

gdb/testsuite/ChangeLog:

	* gdb.arch/riscv-unwind-long-insn-6.s: Remove use of 'I' in
	comment.
	* gdb.arch/riscv-unwind-long-insn-8.s: Likewise.

gdb/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2019-06-05  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* gdb.arch/riscv-unwind-long-insn-6.s: Remove use of 'I' in
+	comment.
+	* gdb.arch/riscv-unwind-long-insn-8.s: Likewise.
+
 2019-06-05  Andrew Burgess  <andrew.burgess@embecosm.com>
 
 	* gdb.arch/riscv-unwind-long-insn-6.s: New file.

gdb/testsuite/gdb.arch/riscv-unwind-long-insn-6.s

@@ -29,7 +29,7 @@ bar:
 func:
         /* A fake 6 byte instruction.  This is never executed, but the
 	   prologue scanner will try to decode it.  These long
-	   instructions are ISA extensions, I use .byte rather than an
+	   instructions are ISA extensions, use .byte rather than an
 	   actual instruction mnemonic so that the test can be compiled
 	   with a toolchain that doesn't include any long instruction
 	   extensions.  */

gdb/testsuite/gdb.arch/riscv-unwind-long-insn-8.s

@@ -29,7 +29,7 @@ bar:
 func:
         /* A fake 8 byte instruction.  This is never executed, but the
 	   prologue scanner will try to decode it.  These long
-	   instructions are ISA extensions, I use .byte rather than an
+	   instructions are ISA extensions, use .byte rather than an
 	   actual instruction mnemonic so that the test can be compiled
 	   with a toolchain that doesn't include any long instruction
 	   extensions.  */