arm64: kaslr: add kaslr_early_init() declaration

kaslr_early_init() is called from assembler code and does not
need a declaration to work, but adding one anyway shuts up
this W=1 warning:

arch/arm64/kernel/pi/kaslr_early.c:88:16: error: no previous prototype for 'kaslr_early_init' [-Werror=missing-prototypes]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20230516160642.523862-13-arnd@kernel.orgSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/archrandom.h

@@ -129,4 +129,6 @@ static inline bool __init __early_cpu_has_rndr(void)
 	return (ftr >> ID_AA64ISAR0_EL1_RNDR_SHIFT) & 0xf;
 }
 
+u64 kaslr_early_init(void *fdt);
+
 #endif /* _ASM_ARCHRANDOM_H */