ipa: fix compile-testing with qcom-mdt=m

ipa: fix compile-testing with qcom-mdt=m

There are multiple drivers that use the qualcomm mdt loader, but they
have conflicting ideas of how to deal with that dependency when compile-testing
for non-qualcomm targets:

IPA only enables the MDT loader when the kernel config includes ARCH_QCOM,
but the newly added ath12k support always enables it, which leads to a
link failure with the combination of IPA=y and ATH12K=m:

    aarch64-linux-ld: drivers/net/ipa/ipa_main.o: in function `ipa_firmware_load':
    ipa_main.c:(.text.unlikely+0x134): undefined reference to `qcom_mdt_load

The ATH12K method seems more reliable here, so change IPA over to do the same
thing.

Fixes: 38a4066f593c ("net: ipa: support COMPILE_TEST")
Fixes: c0dd3f4f7091 ("wifi: ath12k: enable ath12k AHB support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20250731080024.2054904-1-arnd@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>