x86/mm: Remove duplicated word in warning message

Commit bbeb69c ("x86/mm: Remove CONFIG_HIGHMEM64G support") introduces
a new warning message MSG_HIGHMEM_TRIMMED, which accidentally introduces a
duplicated 'for for' in the warning message.

Remove this duplicated word.

This was noticed while reviewing for references to obsolete kernel build
config options.

Fixes: bbeb69c ("x86/mm: Remove CONFIG_HIGHMEM64G support")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-janitors@vger.kernel.org
Link: https://lore.kernel.org/r/20250516090810.556623-1-lukas.bulwahn@redhat.com

Author: bulwahn

arch/x86/mm/init_32.c

@@ -565,7 +565,7 @@ static void __init lowmem_pfn_init(void)
 	"only %luMB highmem pages available, ignoring highmem size of %luMB!\n"
 
 #define MSG_HIGHMEM_TRIMMED \
-	"Warning: only 4GB will be used. Support for for CONFIG_HIGHMEM64G was removed!\n"
+	"Warning: only 4GB will be used. Support for CONFIG_HIGHMEM64G was removed!\n"
 /*
  * We have more RAM than fits into lowmem - we try to put it into
  * highmem, also taking the highmem=x boot parameter into account: