prusa-mk4: set the OTP BOM ID so xBuddy machines boot (#188)

Every xBuddy machine here -- prusa-mk4-*, prusa-mk3-*, prusa-iX-* -- shares the
one OTP_v4 initializer in mk4_init(), which left .bomID unset, i.e. 0. Recent
firmware calls Configuration::check_bom_compatible() (src/hw/xbuddy/
hw_configuration.cpp) before USB is up, and 0 fails it: the machine dies on
bsod("BOM ID not compatible") with a rendered screen but no cdc.log output at
all, which reads as broken logging rather than a stopped firmware.

38 is a shipped customer board. The bound is >=37, plus the legacy 12/14 (not
on MK3.5); iX needs >=1.

Note this is not the "27"/"34" in the datamatrix -- that is the board revision,
a different field. otp_get_bom_id() reads the dedicated byte.

Co-authored-by: D.R.racer <drracer@drracer.eu>
Co-authored-by: vintagepc <53943260+vintagepc@users.noreply.github.com>

Author: 3 people

hw/arm/prusa/prusa-mk4.c

@@ -430,7 +430,11 @@ static void mk4_init(MachineState *machine)
     Object* periphs = machine_get_container("peripheral");
 	const mk4_cfg_t cfg = *mc->cfg;
 
-	OTP_v4 otp_data = { .version = 4, .size = sizeof(OTP_v4),
+	// .bomID is the dedicated OTP byte read by otp_get_bom_id(), not the datamatrix
+	// revision digits. Unset it is 0, which the firmware's check_bom_compatible()
+	// rejects at boot with bsod("BOM ID not compatible") -- it needs >=37 (or the
+	// legacy 12/14). 38 is a shipped customer board.
+	OTP_v4 otp_data = { .version = 4, .size = sizeof(OTP_v4), .bomID = 38,
 		.datamatrix = {'4', '5', '5', '8', '-', '2', '7', '0', '0', '0', '0', '1', '9', '0', '0', '5', '2', '5', '9', '9', '9', '9', 0, 0}
 	};
 	if (cfg.dm_ver == 34)