mwlwifi: add pending patch to fix compilation with kernel 6.12

mwlwifi: add pending patch to fix compilation with kernel 6.12

Building against recent kernel versions (noticed with 6.12) and -Werror
can fail because a macro MAX(a,b) is already defined in minmax.h or
kernel.h before 5.10.

In file included from ../mwlwifi-2025.02.06~db97edf2/hif/fwcmd.h:23,
                 from ../mwlwifi-2025.02.06~db97edf2/core.c:25:
../mwlwifi-2025.02.06~db97edf2/hif/hostcmd.h:1124:9: error: "MAX" redefined [-Werror]
 1124 | #define MAX(a, b) (((a) > (b)) ? (a) : (b))
      |         ^~~
In file included from usr/include/mac80211-backport/linux/minmax.h:4,
                 from ./include/linux/kernel.h:28,
                 from usr/include/mac80211-backport/linux/kernel.h:3,
                 from ./include/linux/skbuff.h:13,
                 from usr/include/mac80211-backport/linux/skbuff.h:3,
                 from ./include/linux/if_ether.h:19,
                 from usr/include/mac80211-backport/linux/if_ether.h:3,
                 from ./include/linux/etherdevice.h:20,
                 from usr/include/mac80211-backport/linux/etherdevice.h:3,
                 from ../mwlwifi-2025.02.06~db97edf2/core.c:18:
./include/linux/minmax.h:330:9: note: this is the location of the previous definition
  330 | #define MAX(a,b) __cmp(max,a,b)
      |         ^~~

Add a pending upstream patch which replaces the MAX(a,b) macro to avoid
conflicts and allow compilation with 6.12

Signed-off-by: Stefan Kalscheuer <stefan@stklcode.de>
Link: https://github.com/openwrt/openwrt/pull/18980
Signed-off-by: Robert Marko <robimarko@gmail.com>