drm/amdgpu: Fix signedness bug in __amdgpu_eeprom_xfer()

drm/amdgpu: Fix signedness bug in __amdgpu_eeprom_xfer()

The i2c_transfer() function returns negatives or else the number of
messages transferred.  This code does not work because ARRAY_SIZE()
is type size_t and so that means negative values of "r" are type
promoted to high positive values which are greater than the ARRAY_SIZE().

Fix this by changing the < to != which works regardless of type
promotion.

Fixes: 746b584762e452 ("drm/amdgpu: Fixes to the AMDGPU EEPROM driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>