rtc: interface: Change type of 'count' from int to u64

Callers of hrtimer_forward_now() should save the return value in u64.
function rtc_pie_update_irq() stores it in variable 'count' of type int
change type of count from unsigned long to u64 to solve the issue.

Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Link: https://lore.kernel.org/r/20190618042351.9692-1-puranjay12@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>