libdvbv5: avoid playing with memory

libdvbv5: avoid playing with memory

Instead of reallocating the memory size for every single table,
just use the known size of the structure, as this is fixed.

The pat table here is an special case, due to the way its struct
is mapped. It is probably a good idea to use malloc there for the
struct dvb_table_pat_program program, but this would break compatibility
with libdvbv5 apps. So, let's keep it as-is.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>