i2c: mt7621: Use devm_clk_get_enabled()

Replace the pair of functions, devm_clk_get() and clk_prepare_enable(),
with a single function devm_clk_get_enabled().

Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>