ADD: @marshmellows fixes for t55x7 reading signal.

ADD: @marshmellows "diphase" definition for T55x7.
MOV: extracted the aquisition from the t55x7 methods and put them inside lfsampling.c
FIX: pcf7931 write,   there is 16bytes in a block.. not 4 as I thought before.
FIX: t55x7 lowered the WRITE_0 to 16.  Even bigger gap.

armsrc/lfsampling.h

@@ -1,6 +1,12 @@
 #ifndef LFSAMPLING_H
 #define LFSAMPLING_H
 
+/**
+* acquisition of T55x7 LF signal. Similart to other LF, but adjusted with @marshmellows thresholds
+* the data is collected in BigBuf.
+**/
+void doT55x7Acquisition(void);
+
 /**
 * Initializes the FPGA for reader-mode (field on), and acquires the samples.
 * @return number of bits sampled