nvk/heap: Set the right pitch for heap resize copies

nvk/heap: Set the right pitch for heap resize copies

Otherwise, once we need to grow past 2^17 B, we attempt to copy two
lines, the hardware errors out, and we get left with a junk heap.
While we're here, re-arrange the code a bit so we keep all the P_FOO
together.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24326>