net: (cpts) fix a missing check of clk_prepare

net: (cpts) fix a missing check of clk_prepare

BugLink: https://bugs.launchpad.net/bugs/1855787
[ Upstream commit 2d822f2dbab7f4c820f72eb8570aacf3f35855bd ]

clk_prepare() could fail, so let's check its status, and if it fails,
return its error code upstream.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>