staging: rtl8723bs: remove custom FIELD_OFFSET macro

The custom FIELD_OFFSET macro is no longer used in the driver (replaced
by standard offsetof). Remove the definition.

Signed-off-by: Navaneeth K <knavaneeth786@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://patch.msgid.link/20251125112059.16913-6-knavaneeth786@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: cyberkunju

drivers/staging/rtl8723bs/include/basic_types.h

@@ -14,8 +14,6 @@
 #include <linux/types.h>
 #include <linux/stddef.h>
 
-#define FIELD_OFFSET(s, field)	((__kernel_ssize_t)&((s *)(0))->field)
-
 #define SIZE_PTR __kernel_size_t
 #define SSIZE_PTR __kernel_ssize_t