Revert "miniflow: Remove unused values_inline branch from miniflow_move()"

This reverts commit 29d2aa3aa74ab97df0f00af5bddaa12485c1d39a.

Turns out the code was correct but the dynamic nature of miniflow
inline storage was poorly documented.  A following patch fixes the
documentation.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
lib/flow.h: Improve struct miniflow comment and definition.

Miniflows can nowadays be dynamically allocated to different inline
sizes, as done by lib/classifier.c, but this had not been documented
at the struct miniflow definition.

Also, MINI_N_INLINE had a different value for 32-bit and 64-bit builds
due to a historical reason.  Now we use 8 for both.

Finally, use change the storage type of 'values_inline' to uint8_t, as
uint64_t looks kind of wide for a boolean, even though we intend the
bit be carved out from the uint64_t where 'map' resides.

Suggested-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>