Fix some Infer Dead Store warnings

[fabio-porcedda]

Fix some Dead Store warnings found by the Infer static analysis tool:

csv.c:53: error: Dead Store
The value written to &efi_status is never used.
51. parse_csv_data(char *data, char *data_end, size_t n_columns, list_t *list)
52. {
53. EFI_STATUS efi_status = EFI_OUT_OF_RESOURCES; ^
54. char delims[] = "\r\n";
55. char *line = data;

fallback.c:71: error: Dead Store
The value written to &dp is never used.
69. EFI_DEVICE_PATH **Out)
70. {
71. EFI_DEVICE_PATH *dp = In; ^
72. if (!In || !Out)
73. return EFI_INVALID_PARAMETER;

post-process-pe.c:125: error: Dead Store
The value written to &PEHdr is never used.
123. {
124. EFI_IMAGE_DOS_HEADER *DOSHdr = data;
125. EFI_IMAGE_OPTIONAL_HEADER_UNION *PEHdr = data; ^
126. size_t HeaderWithoutDataDir, SectionHeaderOffset, OptHeaderSize;
127. size_t FileAlignment = 0;

post-process-pe.c:393: error: Dead Store
The value written to &Section is never used.
391. } 392.
393. Section = ctx->FirstSection; ^
394. for (i=0, Section = ctx->FirstSection; i < ctx->NumberOfSections; i++, Section++) {
395. debug(NOISE, "Section %d has WRITE=%d and EXECUTE=%d\n", i,

[vathpela]

I'd rather remove the assignment later and leave it with a "default" error code; if code gets added later that'll ensure it's not returned uninitialized.