qpg: remove MBEDTLS_REPO_DIR make argument

[q-thla]

This argument is obsolete and this change was accidentally omitted from previous PR's.

[github-actions]

PR #26507: Size comparison from b3b2dc2 to 9098885

Full report (1 build for cc32xx)

platform	target	config	section	b3b2dc2	9098885	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL		0	0	0	0.0
			(read only)	605002	605002	0	0.0
			(read/write)	204164	204164	0	0.0
			.ARM.attributes	44	44	0	0.0
			.ARM.exidx	8	8	0	0.0
			.bss	197576	197576	0	0.0
			.comment	206	206	0	0.0
			.data	1468	1468	0	0.0
			.debug_abbrev	957619	957619	0	0.0
			.debug_aranges	101232	101232	0	0.0
			.debug_frame	342080	342080	0	0.0
			.debug_info	19674626	19674626	0	0.0
			.debug_line	2671903	2671903	0	0.0
			.debug_line_str	513	513	0	0.0
			.debug_loc	33340	33340	0	0.0
			.debug_loclists	1491139	1491139	0	0.0
			.debug_ranges	4984	4984	0	0.0
			.debug_rnglists	94412	94412	0	0.0
			.debug_str	3131828	3131828	0	0.0
			.ramVecs	780	780	0	0.0
			.resetVecs	64	64	0	0.0
			.rodata	104314	104314	0	0.0
			.shstrtab	265	265	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	483089	483089	0	0.0
			.symtab	287232	287232	0	0.0
			.text	498564	498564	0	0.0