powerpc/mpic_timer: fix convert ticks to time subtraction overflow
powerpc/mpic_timer: fix convert ticks to time subtraction overflow

In some cases tmp_sec may be greater than ticks, because in the process
of calculation ticks and tmp_sec will be rounded.

Signed-off-by: Wang Dongsheng <5960aaaba185a50e91c7ab03e3fa96b745a59480@freescale.com>
Signed-off-by: Scott Wood <b77916c2feab81a70245e7b5671f4f02730ebf64@freescale.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs