arch/loongarch: Fix minimal GCC version for target arch options

As reported by Thomas in [1], autobuilders reported host-gcc-initial
failures at configure time, with message:

    Unknown arch in --with-arch=la64v1.0

Both la64v1.0 and la64v1.1 requires GCC 14 as minimum, introduced in
upstream commit [2].

[1] https://lore.kernel.org/buildroot/20250709225522.0a12e583@windsurf/
[2] https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b4ebdd153b2b068082b452772095260b03b78cc2

Fixes: https://autobuild.buildroot.org/results/04a904f08d6e0aacbd308692c99e77a334d72b95/
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
[Julien:
 - add links to mailing list and upstream commit
 - remove unrelated comment change to previous commit
]
Signed-off-by: Julien Olivain <ju.o@free.fr>

arch/Config.in.loongarch

@@ -13,14 +13,14 @@ config BR2_loongarch64_generic
 config BR2_loongarch64_v1_0
 	bool "LoongArch64 ISA version 1.0"
 	depends on BR2_ARCH_IS_64
-	select BR2_ARCH_NEEDS_GCC_AT_LEAST_13
+	select BR2_ARCH_NEEDS_GCC_AT_LEAST_14
 	help
 	  LoongArch64 ISA version 1.0 processor.
 
 config BR2_loongarch64_v1_1
 	bool "LoongArch64 ISA version 1.1"
 	depends on BR2_ARCH_IS_64
-	select BR2_ARCH_NEEDS_GCC_AT_LEAST_13
+	select BR2_ARCH_NEEDS_GCC_AT_LEAST_14
 	help
 	  LoongArch64 ISA version 1.1 processor.