cdc: fix line_coding aligment

[jbtheou]

While calling tud_cdc_n_get_line_coding, the structure is copied into the destination.

Dump of assembler code for function tud_cdc_n_get_line_coding:
0x000193f4 <+0>: mov.w r2, #2112 @ 0x840
0x000193f8 <+4>: ldr r3, [pc, #20] @ (0x19410
<tud_cdc_n_get_line_coding+28>)
0x000193fa <+6>: mla r0, r2, r0, r3
=> 0x000193fe <+10>: ldr.w r3, [r0, #6]
0x00019402 <+14>: str r3, [r1, #0]

On some platform (tested on LPC55S28), the address needs to be 4-bytes aligned. Without this, the address is

(gdb) p &_cdcd_itf.line_coding
$3 = (cdc_line_coding_t *) 0x40100006 <_cdcd_itf+6>

which leads to a HardFault. With this fix

(gdb) p &_cdcd_itf.line_coding
$5 = (cdc_line_coding_t *) 0x40100008 <_cdcd_itf+8>

and the function can be called properly

[hathach]

Thank you, I push an update to add aligned 4 for host driver as well. Actually, this isn't issue since M4+ can access non-aligned data. However iirc lpc55 eventhough is m33 but its highspeed usb can only access 4-bytes aligned memory region which cause the issue. (fs usb probably work just fine).

[jbtheou]

Thanks a lot for extending the fix.
Indeed, used it on SAMD21/51 in the past without issue, so I was a bit confused initially about the issue.

Thank you for the quick review and approval!