misc: rtsx: Fix clang -Wsometimes-uninitialized in rts5261_init_from_hw()

Clang warns:

  drivers/misc/cardreader/rts5261.c:406:13: error: variable 'setting_reg2' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
          } else if (efuse_valid == 0) {
                     ^~~~~~~~~~~~~~~~
  drivers/misc/cardreader/rts5261.c:412:30: note: uninitialized use occurs here
          pci_read_config_dword(pdev, setting_reg2, &lval2);
                                      ^~~~~~~~~~~~

efuse_valid == 1 is not a valid value so just return early from the
function to avoid using setting_reg2 uninitialized.

Fixes: b1c5f308

 ("misc: rtsx: add rts5261 efuse function")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Tom Rix <trix@redhat.com>
Suggested-by: Ricky WU <ricky_wu@realtek.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20220523150521.2947108-1-nathan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>