HID: i2c-hid: fix kerneldoc warnings in i2c-hid-core.c

Fix following warnings caused by mismatch bewteen function parameters
and comments.
drivers/hid/i2c-hid/i2c-hid-core.c:331: warning: Function parameter or member 'data_len' not described in 'i2c_hid_set_or_send_report'
drivers/hid/i2c-hid/i2c-hid-core.c:331: warning: Excess function parameter 'len' description in 'i2c_hid_set_or_send_report'

Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>