riscv: fix spacing in struct pt_regs

Replace 8 spaces with tab to match styling.
Signed-off-by: David Abdurachmanov <david.abdurachmanov@gmail.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

arch/riscv/include/asm/ptrace.h

@@ -56,8 +56,8 @@ struct pt_regs {
 	unsigned long sstatus;
 	unsigned long sbadaddr;
 	unsigned long scause;
-        /* a0 value before the syscall */
-        unsigned long orig_a0;
+	/* a0 value before the syscall */
+	unsigned long orig_a0;
 };
 
 #ifdef CONFIG_64BIT