soc: sifive: ccache: use pr_fmt() to remove CCACHE: prefixes

Use the pr_fmt() macro to prefix all the output with "CCACHE:"
to avoid having to write it out each time, or make a large diff
when the next change comes along.

Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20220913061817.22564-6-zong.li@sifive.com


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>