riscv: Trace irq on only interrupt is enabled

We should call irq trace only if interrupt is going to be enabled during
excecption handling. Otherwise, it results in following warning during
boot with lock debugging enabled.

[    0.000000] ------------[ cut here ]------------
[    0.000000] DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled)
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:4085 lockdep_hardirqs_on_prepare+0x22a/0x22e
[    0.000000] Modules linked in:
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.10.0-00022-ge20097fb37e2-dirty #548
[    0.000000] epc: c005d5d4 ra : c005d5d4 sp : c1c01e80
[    0.000000]  gp : c1d456e0 tp : c1c0a980 t0 : 00000000
[    0.000000]  t1 : ffffffff t2 : 00000000 s0 : c1c01ea0
[    0.000000]  s1 : c100f360 a0 : 0000002d a1 : c00666ee
[    0.000000]  a2 : 00000000 a3 : 00000000 a4 : 00000000
[    0.000000]  a5 : 00000000 a6 : c1c6b390 a7 : 3ffff00e
[    0.000000]  s2 : c2384fe8 s3 : 00000000 s4 : 00000001
[    0.000000]  s5 : c1c0a980 s6 : c1d48000 s7 : c1613b4c
[    0.000000]  s8 : 00000fff s9 : 80000200 s10: c1613b40
[    0.000000]  s11: 00000000 t3 : 00000000 t4 : 00000000
[    0.000000]  t5 : 00000001 t6 : 00000000

Fixes: 3c469798 ("riscv:Enable LOCKDEP_SUPPORT & fixup TRACE_IRQFLAGS_SUPPORT")

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>