powerpc: Don't use a function descriptor for system call table

There is no need to create a function descriptor for the system call
table. By using one we force the system call table into the text
section and it really belongs in the rodata section.

This also removes another use of dot symbols.

Signed-off-by: Anton Blanchard <anton@samba.org>

diff --cc arch/powerpc/kernel/entry_64.S
Simple merge

diff --cc arch/powerpc/kernel/systbl.S
Simple merge