misc: rcc: keep the rcc device name for subnode

misc: rcc: keep the rcc device name for subnode

Update the name associated with the RCC drivers to avoid
duplicated name with the driver name.

With this patch the traces displayed with log macro provide a
correct device name.

The rcc device name before the patch is:

 Class     Index  Probed  Driver                Name
-----------------------------------------------------------
 root          0  [ + ]   root_driver           root_driver
 simple_bus    0  [ + ]   simple_bus            |-- soc
 (...)
 nop           0  [ + ]   stm32-rcc             |   |-- rcc@50000000
 clk           0  [ + ]   stm32mp1_clk          |   |   |-- stm32mp1_clk
 reset         0  [ + ]   stm32_rcc_reset       |   |   `-- stm32_rcc_reset

And they become:
 (...)
 nop           0  [ + ]   stm32-rcc             |   |-- rcc@50000000
 clk           0  [ + ]   stm32mp1_clk          |   |   |-- rcc@50000000
 reset         0  [ + ]   stm32_rcc_reset       |   |   `-- rcc@50000000

The traces is correct:
stm32mp1_clk rcc@stm32mp1_clk: .....
=>
stm32mp1_clk rcc@50000000: .....

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>