riscv: extable: use `ex` for `exception_table_entry`

The var name "fixup" is a bit confusing, since this is a
exception_table_entry. Use "ex" instead  to refer to an entire entry.
In subsequent patches we'll use `fixup` to refer to the fixup
field specifically.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/mm/extable.c

@@ -13,15 +13,15 @@
 
 bool fixup_exception(struct pt_regs *regs)
 {
-	const struct exception_table_entry *fixup;
+	const struct exception_table_entry *ex;
 
-	fixup = search_exception_tables(regs->epc);
-	if (!fixup)
+	ex = search_exception_tables(regs->epc);
+	if (!ex)
 		return false;
 
 	if (regs->epc >= BPF_JIT_REGION_START && regs->epc < BPF_JIT_REGION_END)
-		return rv_bpf_fixup_exception(fixup, regs);
+		return rv_bpf_fixup_exception(ex, regs);
 
-	regs->epc = (unsigned long)&fixup->fixup + fixup->fixup;
+	regs->epc = (unsigned long)&ex->fixup + ex->fixup;
 	return true;
 }