platform/x86: dell-smo8800: remove redundant assignments to byte_data

Variable byte_data is being initialized and re-assigned with values that
are never read. Remove these as these redundant assignments. Cleans up
clang warning:

drivers/platform/x86/dell-smo8800.c:106:2: warning: Value stored to 'byte_data'
is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>