usb: gadget: replace %p with %pK

Format specifier %p can leak kernel addresses while not valuing the
kptr_restrict system settings. When kptr_restrict is set to (1), kernel
pointers printed using the %pK format specifier will be replaced with 0's.
Debugging Note : &pK prints only Zeros as address. If you need actual
address information, write 0 to kptr_restrict.

echo 0 > /proc/sys/kernel/kptr_restrict

Change-Id: Ice16947924f56b8f4244ae03b9ab4f2e36b7d56b
Signed-off-by: Vamsi Krishna Samavedam <vskrishn@codeaurora.org>
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>