The module alias platform tag contains a spelling mistake. Fix it.

Fixes: f33506abbcdd ("rtc: bd70528: Add MODULE ALIAS to autoload module")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20191106083418.159045-1-colin.king@canonical.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>