Revert "arch: arc: add sys_write64/sys_read64 functions"

This reverts commit 3462a48 that
was marked as hotfix and merged despite reservations from
ARC maintainer

Signed-off-by: Benjamin Cabé <[email protected]>

Author: kartben

include/zephyr/arch/arc/sys-io-common.h

@@ -74,24 +74,6 @@ static ALWAYS_INLINE void sys_write32(uint32_t data, mem_addr_t addr)
 	compiler_barrier();
 }
 
-static ALWAYS_INLINE uint64_t sys_read64(mem_addr_t addr)
-{
-	uint64_t value;
-
-	compiler_barrier();
-	value = *(volatile uint64_t *)addr;
-	compiler_barrier();
-
-	return value;
-}
-
-static ALWAYS_INLINE void sys_write64(uint64_t data, mem_addr_t addr)
-{
-	compiler_barrier();
-	*(volatile uint64_t *)addr = data;
-	compiler_barrier();
-}
-
 #ifdef __cplusplus
 }
 #endif