HID: amd_sfh: Add missing check for dma_alloc_coherent

Add check for the return value of the dma_alloc_coherent since
it may return NULL pointer if allocation fails.

Fixes: 4b2c53d9

 ("SFH:Transport Driver to add support of AMD Sensor Fusion Hub (SFH)")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Acked-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Link: https://lore.kernel.org/r/20221220024921.21992-1-jiasheng@iscas.ac.cn