x86/tlb: Convert copy_from_user() + kstrtouint() to kstrtouint_from_user()

x86/tlb: Convert copy_from_user() + kstrtouint() to kstrtouint_from_user()

Using kstrtouint_from_user() instead of copy_from_user() + kstrtouint() makes
the code simpler and less error-prone.

No functional changes.

  [ bp: Align function args on opening brace, while at it. ]

Suggested-by: Yury Norov <ynorov@nvidia.com>
Signed-off-by: Fushuai Wang <wangfushuai@baidu.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Yury Norov <ynorov@nvidia.com>
Link: https://patch.msgid.link/20260117145615.53455-3-fushuai.wang@linux.dev