[PATCH v4] drivers: fpga: Use FPGA_INTEL_SDM_MAILBOX conditional instead of Agilex/Stratix10

[LOK, CHEN HUEI]

Hi Michal,

Following up on this v4 -- this addresses Tien Fong's review from v3
by switching to CONFIG_FPGA_INTEL_SDM_MAILBOX as the conditional
instead of the per-SoC arch checks.

> Replace the conditional compilation checks for
> CONFIG_ARCH_SOCFPGA_AGILEX and CONFIG_ARCH_SOCFPGA_STRATIX10 with
> CONFIG_FPGA_INTEL_SDM_MAILBOX.
>
> Signed-off-by: drosdi <danish.ahmad.rosdi at altera.com>
> Signed-off-by: Chen Huei Lok <chen.huei.lok at altera.com>
> ---
> v3->v4:
> --------
> Replace conditional check with CONFIG_FPGA_INTEL_SDM_MAILBOX.

Tien Fong, could you provide your Reviewed-by if this looks correct
to you?

Thanks,
Lok