staging: r8188eu: we use a constant number of hw_xmit entries

struct xmit_priv contains a pointer to an array of struct hw_xmit entries.
xmit_priv's (ill-named) hwxmit_entry component stores the size of this
array, i.e. the number of hw_xmit entries that are used.

The array size is constant, it's initialised to HWXMIT_ENTRY and never
updated. Simplify the code accordingly. Remove hwxmit_entry, do not pass
the array size as a function parameter and use HWXMIT_ENTRY in the code
that handles the array.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Link: https://lore.kernel.org/r/20230123205342.229589-2-martin@kaiser.cx


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>