riscv: fix bugon.cocci warnings

Use BUG_ON instead of a if condition followed by BUG.

Generated by: scripts/coccinelle/misc/bugon.cocci

Fixes: c22b0bcb ("riscv: Add kprobes supported")
CC: Guo Ren <guoren@linux.alibaba.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: kernel test robot <lkp@intel.com>
Signed-off-by: Julia Lawall <julia.lawall@inria.fr>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/kernel/probes/kprobes.c

@@ -256,8 +256,7 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr)
 		 * normal page fault.
 		 */
 		regs->epc = (unsigned long) cur->addr;
-		if (!instruction_pointer(regs))
-			BUG();
+		BUG_ON(!instruction_pointer(regs));
 
 		if (kcb->kprobe_status == KPROBE_REENTER)
 			restore_previous_kprobe(kcb);