ANDROID: GKI: add sg_copy_from/to_buffer to virtual device symbol list

In commit 5ae5060e ("mmc: mmci: stm32: fix DMA API overlapping
mappings warning"), the driver calls out to sg_copy_from/to_buffer() so
add it to the virtual symbol list so that build target continues to work
properly.

Fixes: 5ae5060e ("mmc: mmci: stm32: fix DMA API overlapping mappings warning")
Change-Id: I1f028da6708ea3745a7a5cd29627b3ab047d17b0
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>