can: pch_can: pch_can_error(): initialize errc before using it

can: pch_can: pch_can_error(): initialize errc before using it

After commit cafa6337968f, the variable errc is accessed before being
initialized, c.f. below W=2 warning:

| In function 'pch_can_error',
|     inlined from 'pch_can_poll' at drivers/net/can/pch_can.c:739:4:
| drivers/net/can/pch_can.c:501:29: warning: 'errc' may be used uninitialized [-Wmaybe-uninitialized]
|   501 |                 cf->data[6] = errc & PCH_TEC;
|       |                             ^
| drivers/net/can/pch_can.c: In function 'pch_can_poll':
| drivers/net/can/pch_can.c:484:13: note: 'errc' was declared here
|   484 |         u32 errc, lec;
|       |             ^~~~

Moving errc initialization up solves this issue.

Fixes: cafa6337968f ("can: pch_can: do not report txerr and rxerr during bus-off")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/all/20220721160032.9348-1-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>