fs/ntfs3: handle hdr_first_de() return value

In the Linux kernel, the following vulnerability has been resolved:

fs/ntfs3: handle hdr_first_de() return value

The hdr_first_de() function returns a pointer to a struct NTFS_DE. This

pointer may be NULL. To handle the NULL error effectively, it is important

to implement an error handler. This will help manage potential errors

consistently.

Additionally, error handling for the return value already exists at other

points where this function is called.

Found by Linux Verification Center (linuxtesting.org) with SVACE.