[media] msi001: fix possible integer overflow

Coverity CID 1196502: Unintentional integer overflow
(OVERFLOW_BEFORE_WIDEN)

Potentially overflowing expression "(f_rf + f_if + f_if1) * lo_div"
with type "unsigned int" (32 bits, unsigned) is evaluated using 32-bit
arithmetic before being used in a context which expects an expression
of type "u64" (64 bits, unsigned). To avoid overflow, cast either
operand to "u64" before performing the multiplication.

Reported-by:  <scan-admin@coverity.com>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>