arm64: mte: Remove unused mte_assign_mem_tag_range()

mte_assign_mem_tag_range() was added in commit 85f49ca
("arm64: mte: add in-kernel MTE helpers") in 5.11 but moved out of
mte.S by commit 2cb3427 ("arm64: kasan: simplify and inline
MTE functions") in 5.12 and renamed to mte_set_mem_tag_range().
2cb3427 did not delete the old function prototypes in mte.h.

Remove the unused prototype from mte.h.

Cc: Will Deacon <will@kernel.org>
Reported-by: Derrick McKee <derrick.mckee@gmail.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20210407133817.23053-1-vincenzo.frascino@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/mte.h

@@ -47,8 +47,6 @@ long get_mte_ctrl(struct task_struct *task);
 int mte_ptrace_copy_tags(struct task_struct *child, long request,
 			 unsigned long addr, unsigned long data);
 
-void mte_assign_mem_tag_range(void *addr, size_t size);
-
 #else /* CONFIG_ARM64_MTE */
 
 /* unused if !CONFIG_ARM64_MTE, silence the compiler */
@@ -84,10 +82,6 @@ static inline int mte_ptrace_copy_tags(struct task_struct *child,
 	return -EIO;
 }
 
-static inline void mte_assign_mem_tag_range(void *addr, size_t size)
-{
-}
-
 #endif /* CONFIG_ARM64_MTE */
 
 #endif /* __ASSEMBLY__ */