media: pwc: remove useless header files

It was originally intended to introduce simple_strtol,
but since commit a081c3400ff2 ("[media] pwc: Remove dev_hint
module parameter"), that simple_strtol has been removed,
so in order to prevent disputes, the header file should be removed.

Signed-off-by: Zhang Heng <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
[hverkuil: fixed small typos in commit log]

drivers/media/usb/pwc/pwc-if.c

···
 #endif
 #include <linux/vmalloc.h>
 #include <asm/io.h>
-#include <linux/kernel.h>		/* simple_strtol() */
 
 #include "pwc.h"
 #include "pwc-kiara.h"