HID: picolcd: prevent NULL pointer dereference in picolcd_send_and_wait()

In the Linux kernel, the following vulnerability has been resolved: HID: picolcd: prevent NULL pointer dereference in picolcd_send_and_wait() In picolcd_send_and_wait(), an integer overflow of the signed loop counter 'k' can theoretically lead to a NULL pointer dereference of 'raw_data'. If the loop executes more than INT_MAX times, 'k' becomes negative, making the condition 'k < size' true even when 'size' is 0. Change the type of 'k' to 'unsigned int' to prevent the overflow and eliminate the out-of-bounds access. Found by Linux Verification Center (linuxtesting.org) with the Svace static analysis tool. [jkosina@suse.com: extended hash length]