[Utils][vim] Match more hexadecimal float constants (#99000)

The `0x[KLMHR]` syntax denotes different floating-point types: various
long doubles, half and bfloat.

See https://llvm.org/docs/LangRef.html#simple-constants for reference.

Author: frasercrmck

llvm/utils/vim/syntax/llvm.vim

@@ -219,7 +219,7 @@ syn keyword llvmError  getresult begin end
 syn match   llvmNoName /[%@!]\d\+\>/
 syn match   llvmNumber /-\?\<\d\+\>/
 syn match   llvmFloat  /-\?\<\d\+\.\d*\(e[+-]\d\+\)\?\>/
-syn match   llvmFloat  /\<0x\x\+\>/
+syn match   llvmFloat  /\<0x[KLMHR]\?\x\+\>/
 syn keyword llvmBoolean true false
 syn keyword llvmConstant zeroinitializer undef null none poison vscale
 syn match   llvmComment /;.*$/