The driver tries to figure out which state a SD clock is in when the
clock is registered, instead of setting a known state. This can be
problematic for two reasons.

1. If the clock driver can't figure out the state of the clock,
   registration of the clock fails, and setting of a known state by a
   clock user is not possible.

2. The state of the clock depends on if and how the bootloader
   configured it. The driver only checks that the rate is known, not if
   the clock is stopped or not for example.

Fix this by setting a known state and making sure the clock is stopped.
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>