meta: Fix hour_type size

meta: Fix hour_type size

In kernel as well as when parsing, hour_type is assumed to be 32bits.
Having the struct datatype field set to 64bits breaks Big Endian and so
does passing a 64bit value and 32 as length to constant_expr_alloc() as
it makes it import the upper 32bits. Fix this by turning 'result' into a
uint32_t and introduce a temporary uint64_t just for the call to
time_parse() which expects that.

Fixes: f8f32deda31df ("meta: Introduce new conditions 'time', 'day' and 'hour'")
Signed-off-by: Phil Sutter <phil@nwl.cc>