x86/process/64: Use savesegment() in __show_regs() instead of inline asm

x86/process/64: Use savesegment() in __show_regs() instead of inline asm

Replace direct 'movl' instructions for DS, ES, FS, and GS read in
__show_regs() with the savesegment() helper. This improves
readability, consistency, and ensures proper handling of
segment registers on x86_64.

No functional change intended.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://patch.msgid.link/20260330085938.67985-2-ubizjak@gmail.com