[Bug target/121062] integer registers of vector constant load shouldn't go through memory

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121062

--- Comment #2 from Uroš Bizjak <ubizjak at gmail dot com> ---
Created attachment 61860
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61860&action=edit
Slightly cleaned version

Slightly cleaned up version of the patch, also fixes splitter for constant
vector stores.