arm64/fpsimd: Remove unused declaration fpsimd_kvm_prepare()

Commit fbc7e61 ("KVM: arm64: Unconditionally save+flush host
FPSIMD/SVE/SME state") removed the implementation but leave declaration.

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20250309070723.1390958-1-yuehaibing@huawei.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/fpsimd.h

@@ -80,7 +80,6 @@ extern void fpsimd_signal_preserve_current_state(void);
 extern void fpsimd_preserve_current_state(void);
 extern void fpsimd_restore_current_state(void);
 extern void fpsimd_update_current_state(struct user_fpsimd_state const *state);
-extern void fpsimd_kvm_prepare(void);
 
 struct cpu_fp_state {
 	struct user_fpsimd_state *st;