hpet: Optimize local variable data type in hpet_alloc()

The local variable period uses at most 32 bits and can be a u32 instead
of unsigned long. The upper 32 bits are all 0 after masking and right
shifting cap by HPET_COUNTER_CLK_PERIOD_SHIFT and can be discarded.

Since do_div() casts the divisor to u32 anyway, changing the data type
of period to u32 also removes the following Coccinelle/coccicheck
warning reported by do_div.cocci:

WARNING: do_div() does a 64-by-32 division, please consider using div64_ul instead

Signed-off-by: Thorsten Blum <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/char/hpet.c

···
 	struct hpets *hpetp;
 	struct hpet __iomem *hpet;
 	static struct hpets *last;
-	unsigned long period;
+	u32 period;
 	unsigned long long temp;
 	u32 remainder;