hv: Select CONFIG_SYSFB only for CONFIG_HYPERV_VMBUS

hv: Select CONFIG_SYSFB only for CONFIG_HYPERV_VMBUS

Hyperv's sysfb access only exists in the VMBUS support. Therefore
only select CONFIG_SYSFB for CONFIG_HYPERV_VMBUS. Avoids sysfb code
on systems that don't need it.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 96959283a58d ("Drivers: hv: Always select CONFIG_SYSFB for Hyper-V guests")
Cc: Michael Kelley <mhklinux@outlook.com>
Cc: Saurabh Sengar <ssengar@linux.microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Long Li <longli@microsoft.com>
Cc: linux-hyperv@vger.kernel.org
Cc: <stable@vger.kernel.org> # v6.16+
Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Link: https://patch.msgid.link/20260402092305.208728-2-tzimmermann@suse.de