[PATCH] drivers/gpu/drm/ast: Fix infinite loop if read fails

[Why] Similar to commit <298360af3>("drivers/gpu/drm/ast: Fix infinite loop if read fails"), ast_init_dram_reg() configures a window in order to access BMC memory. A BMC register can be configured to disallow this, and if so, causes an infinite loop in the ast driver which renders the system unusa

[PATCH] drivers/gpu/drm/ast: Fix infinite loop if read fails

ast_get_dram_info() configures a window in order to access BMC memory. A BMC register can be configured to disallow this, and if so, causes an infinite loop in the ast driver which renders the system unusable. Fix this by erroring out if an error is detected. On powerpc systems with EEH, this lea