xtensa: drop unused field from the struct exc_table

exc_table::syscall_save and corresponding macro EXC_TABLE_SYSCALL_SAVE
have never been used by the xtensa code. Drop them.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/include/asm/traps.h

@@ -25,8 +25,6 @@ struct exc_table {
 	void *fixup;
 	/* For passing a parameter to fixup */
 	void *fixup_param;
-	/* For fast syscall handler */
-	unsigned long syscall_save;
 	/* Fast user exception handlers */
 	void *fast_user_handler[EXCCAUSE_N];
 	/* Fast kernel exception handlers */

arch/xtensa/kernel/asm-offsets.c

@@ -137,8 +137,6 @@ int main(void)
 	DEFINE(EXC_TABLE_DOUBLE_SAVE, offsetof(struct exc_table, double_save));
 	DEFINE(EXC_TABLE_FIXUP, offsetof(struct exc_table, fixup));
 	DEFINE(EXC_TABLE_PARAM, offsetof(struct exc_table, fixup_param));
-	DEFINE(EXC_TABLE_SYSCALL_SAVE,
-	       offsetof(struct exc_table, syscall_save));
 	DEFINE(EXC_TABLE_FAST_USER,
 	       offsetof(struct exc_table, fast_user_handler));
 	DEFINE(EXC_TABLE_FAST_KERNEL,