arch/Config.in.x86: x86-64-v4 implies AVX512

Now that we have BR2_X86_CPU_HAS_AVX512, we can use it to fix the
x86-64-v4 definition, which implies AVX512 support according to
https://gitlab.com/x86-psABIs/x86-64-ABI/-/blob/master/x86-64-ABI/low-level-sys-info.tex

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

arch/Config.in.x86

@@ -146,6 +146,7 @@ config BR2_x86_x86_64_v4
 	select BR2_X86_CPU_HAS_SSE42
 	select BR2_X86_CPU_HAS_AVX
 	select BR2_X86_CPU_HAS_AVX2
+	select BR2_X86_CPU_HAS_AVX512
 	select BR2_ARCH_NEEDS_GCC_AT_LEAST_11
 	help
 	  This option corresponds to the x86-64-v4 micro-architecture