readme.md: Update support status for hexagon and s390

Hexagon's defconfig and allmodconfig work without issues now and most
randconfigs that are tested by 0day do not show many Hexagon specific
issues. The LLVM support has been strong so upgrade it to "relatively
well supported and tested".

The s390 kernel and LLVM folks have been coordinating well to support
building the s390 kernel with clang; upgrade its status for the same
reason.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Author: nathanchance

readme.md

@@ -38,19 +38,19 @@ The following architectures are targetable from both LLVM and the Linux kernel
 and are relatively well supported and tested:
 * arm
 * arm64
+* hexagon
+* s390
 * x86
 
 The following architectures are targetable from both LLVM and the Linux kernel
 and are supported and tested in limited configurations:
 * mips
 * powerpc
 * riscv
-* s390
 
 The following architectures are targetable from both LLVM and the Linux kernel
 but are untested or currently broken:
 * arc
-* hexagon
 * sparc
 
 The following architectures are targetable from the Linux kernel but not LLVM: