fddi/skfp: Avoid the use of one-element array

One-element arrays are being deprecated[1]. Replace the one-element array
with a simple object of type u_char: 'u_char rm_pad1'[2], once it seems
this is just a placeholder for padding.

[1] https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arrays
[2] https://github.com/KSPP/linux/issues/86

Built-tested-by: kernel test robot <[e-mail]>
Link: https://lore.kernel.org/lkml/[e-mail]/
Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/fddi/skfp/h/smc.h

···
 	u_char timer1_exp ;		/* flag : timer 1 expired */
 	u_char timer2_exp ;		/* flag : timer 2 expired */
 
-	u_char rm_pad1[1] ;
+	u_char rm_pad1;
 } ;
 
 /*