usb: gadget: renesas_usbhs: tidyup INTENB0 method
usb: gadget: renesas_usbhs: tidyup INTENB0 method

This patch tidyup Interrupt Enable Register 0 (INTENB0)
which has relationship with picky BEMPENB/BRDYENB.

 - add explain comment
 - ignore nonsense 0 write case

Signed-off-by: Kuninori Morimoto <a3b51ccb87d18302c1692defcfbf83319d1737eb@renesas.com>
Signed-off-by: Felipe Balbi <94dddeeef08b001e003cce128ddc162a4e2c6cd2@ti.com>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs