mmc: sdhci: fixed missing error control

In sdhci.c, sdhci_add_host() didn't perform correct error control. So, We need to add correct error control.
version

v3: [1/2] mmc:sdhci: add error checking for mmc_add_host
* add "unregister for leds class, free buffer and del timer" reviewed by Wolfram Sang.
[2/2] mmc:sdhci: add regulator disable/put when control error
* fixed missing regulator disable/put

 drivers/mmc/host/sdhci.c |   24 ++++++++++++++++++++++--
 1 files changed, 22 insertions(+), 2 deletions(-)