staging: r8188eu: pass only ies to process_p2p_ps_ie

staging: r8188eu: pass only ies to process_p2p_ps_ie

The process_p2p_ps_ie function parses the information elements of a beacon
message and extracts p2p-related info.

process_p2p_ps_ie does not receive a pointer to the information elements
as one would expect. Instead it receives a pointer to the timestamp field
in the beacon message. process_p2p_ps_ie increments this pointer by
_BEACON_IE_OFFSET_ to jump to the start of the information elements (and
decreases the buffer length accordingly).

This is clumsy and hard to understand. Rewrite this such that
process_p2p_ps_ie takes a pointer to the information elements and the
total length of all elements. Check up-front that the total length is
not negative.

Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20221126160129.178697-5-martin@kaiser.cx
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>