net: fs_enet: Use cpm_muram_xxx() functions instead of cpm_dpxxx() macros

cpm_dpxxx() macros are now always referring to cpm_muram_xxx() functions
directly since commit 3dd82a1e ("[POWERPC] CPM: Always use new
binding.")

Use cpm_muram_xxx() functions directly so that the cpm_dpxxx() macros
can be removed in the near future.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/2400b3156891adb653dc387fff6393de10cf2b24.1691155347.git.christophe.leroy@csgroup.eu


Signed-off-by: Jakub Kicinski <kuba@kernel.org>