x86/extable: Remove unused fixup type EX_TYPE_COPY

After

  034ff37d ("x86: rewrite '__copy_user_nocache' function")

rewrote __copy_user_nocache() to use EX_TYPE_UACCESS instead of the
EX_TYPE_COPY exception type, there are no more EX_TYPE_COPY users, so
remove it.

  [ bp: Massage commit message. ]

Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240204082627.3892816-2-tongtiangen@huawei.com