samples/bpf: Fix compilation failure for samples/bpf on LoongArch Fedora

samples/bpf: Fix compilation failure for samples/bpf on LoongArch Fedora

When building the latest samples/bpf on LoongArch Fedora

     make M=samples/bpf

There are compilation errors as follows:

In file included from ./linux/samples/bpf/sockex2_kern.c:2:
In file included from ./include/uapi/linux/in.h:25:
In file included from ./include/linux/socket.h:8:
In file included from ./include/linux/uio.h:9:
In file included from ./include/linux/thread_info.h:60:
In file included from ./arch/loongarch/include/asm/thread_info.h:15:
In file included from ./arch/loongarch/include/asm/processor.h:13:
In file included from ./arch/loongarch/include/asm/cpu-info.h:11:
./arch/loongarch/include/asm/loongarch.h:13:10: fatal error: 'larchintrin.h' file not found
         ^~~~~~~~~~~~~~~
1 error generated.

larchintrin.h is included in /usr/lib64/clang/14.0.6/include,
and the header file location is specified at compile time.

Test on LoongArch Fedora:
https://github.com/fedora-remix-loongarch/releases-info

Signed-off-by: Haoran Jiang <jianghaoran@kylinos.cn>
Signed-off-by: zhangxi <zhangxi@kylinos.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250425095042.838824-1-jianghaoran@kylinos.cn