rust: bindings: fix VM_MAYSHARE blocklist entry

Commit 2b6a3f0 ("mm: declare VMA flags by bit") added constant helpers
for the VMA flags and blocklist entries to suppress their direct bindings.
However, it listed `VM_MAYEXEC` twice and omitted `VM_MAYSHARE`.

Thus fix it.

Fixes: 2b6a3f0 ("mm: declare VMA flags by bit")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Link: https://patch.msgid.link/20260930123645.302318-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: ojeda

rust/bindgen_parameters

@@ -50,7 +50,7 @@
 --blocklist-item VM_MAYREAD
 --blocklist-item VM_MAYWRITE
 --blocklist-item VM_MAYEXEC
---blocklist-item VM_MAYEXEC
+--blocklist-item VM_MAYSHARE
 --blocklist-item VM_PFNMAP
 --blocklist-item VM_IO
 --blocklist-item VM_DONTCOPY